People today use the Netflix service on their computers, but Netflix (NFLX) has cut a series of deals with hardware partners to make the service available on TV sets through an array of devices.

Most of these devices were designed to do other things: a videogame console, high-definition Blu-ray disc players, a TiVo (TIVO) digital video recorder. So to see how well the service works on these devices, I’ve spent the past couple of weeks comparing the Netflix experience on Microsoft’s (MSFT) Xbox 360 game console, on LG Electronics’ BD300 Blu-ray disc player and on a set-top box from Roku called the Netflix Player. The last, as the name implies, is designed mainly for Netflix service.

The devices suffer from a relatively skimpy selection of videos on the Netflix Internet service. Netflix has more than 100,000 titles for rent on disc, but about 12,000 titles for viewing through its Internet service at the moment, and there’s often a months-long delay after a movie’s release before it shows up online. Television shows generally turn up more quickly, with a handful, like NBC’s “Heroes,” watchable the day after they air.

Still, I find the Netflix service very appealing, especially for catching up on episodes of TV series, such as “30 Rock,” that I missed when they aired. Unlike the iTunes Store and other sites that charge users $1.99 per TV episode and $3.99 to rent a movie online, the Netflix Internet service is free to subscribers to its DVD service on one of the company’s “unlimited” rental plans, which start at $8.99 a month.

Depending on how fast your Internet connection is, Netflix videos begin playing almost instantly, though you can’t keep permanent copies.

Connecting the devices to Netflix through my wired home network was easy in all three cases. I used a wireless home network — more common in homes than the wired variety — with the Roku device, the only one of three products that comes with built-in Wi-Fi (it worked well in this mode). People who want to use the Xbox 360 with a wireless network will have to spend $70 or so on an external Wi-Fi adapter. LG recommends people use only a wired home network to connect to Netflix from its player, including adapter kits that cost about $100 for transmitting data over home power lines.

All the devices require you to create a list of movies you want to watch from a computer, just like Netflix subscribers set up “queues” of DVDs to be delivered by mail. The Xbox 360 offered by far the most elegant-looking interface for browsing through videos in my Netflix queue, letting me glide through a long row of cover art representing the movies and TV shows I selected on my PC.

In contrast, the Netflix menu on the LG Blu-ray player and Roku device were more static, making it more awkward to navigate the expanse of titles. Netflix became available on the Xbox 360 in November as part of a more sweeping software upgrade, delivered over the Internet, that remade the graphical look of the system.

The quality of most of the videos on Netflix is, to my eyes, about DVD quality, though Netflix is adding some titles in high-definition to its Internet library. HD titles were available for viewing only through the Xbox 360 when I was testing the service. Roku and LG say they will make software updates available online this month that add HD support to their devices.

The Xbox 360 also has some annoying quirks when using it as a movie player — including a noisy fan I found distracting. The game controller that comes with the Xbox 360 is clunky for playing movies, so users will need to invest in an inexpensive additional remote-control design for media. The Roku and LG players, in contrast, were totally silent and had acceptable remote controls for watching Netflix videos.

I experienced the most serious glitches with the LG Blu-ray player, which occasionally dropped the video signal to my television set as I was watching a movie. LG says the loss of video signal could have been due to the connection I used to hook the player to my TV, though I’ve never had a problem with other devices using the same connection. The LG Blu-ray player also took the longest of all the devices to install software upgrades from the Internet.

While there are some differences in the Netflix experience on the Roku device, Xbox 360 and LG Blu-ray player, none of them is so great that they should trump other considerations — like a desire to play videogames or watch HD Blu-ray movies — in deciding which system is the best fit.

The LG Blu-ray player is available online for about $300. The cheapest Xbox 360 model is $199. (To get Netflix through the Xbox 360, users must be “gold” members to the $49.99-a-year Xbox Live game service.) But if what you’re after is primarily Netflix movies, and you’ve got room near your TV for another box, the $99.99 Roku product is the best value.

Walt Mossberg is on vacation.

Write to Nick Wingfield at nick.wingfield@wsj.com

Amazon (AMZN) launched a new service called Amazon Video on Demand, which allows users, for a fee, to watch any of 40,000 TV episodes or movies, in real time, on their Windows and Macintosh computers, and on specially equipped Sony Bravia TV sets. This service replaces an earlier Amazon video offering called Unbox.

I have been testing Amazon Video on Demand and I found it worked well, although it has some limitations. The user interface is clean and smart, the quality is good if you have a fast Internet connection, and there are some clever features. On the downside, it works poorly with the slow connections typical in places like hotels. And there are some studio-imposed limits on what content is offered and how you can view it.

To date, there have been three major models for legally getting TV shows and movies from the Web.

In one, best represented by Apple’s (AAPL) widely used iTunes store, the TV shows and movies are ad-free, but you pay for each. All of this content is downloaded to your Windows or Macintosh computer or your Apple TV set-top box for later viewing, even when you’re not connected to the Internet — though on Apple TV you can start watching while the material is being downloaded.

A second model, best represented by the studio-owned Hulu.com, presents movies and TV shows on a Windows or Macintosh personal computer free of charge, but requires you to watch commercials that can’t be skipped. The TV shows and movies you view on Hulu are “streamed” rather than downloaded, meaning they are meant to be viewed immediately, in real time, rather than stored for viewing when you’re not connected to the Internet.

The third online model is best represented by Netflix (NFLX), the popular DVD distributor. It offers a “Watch Instantly” streaming option on Windows PCs or on TVs equipped with a special set-top box, for a small portion of its large catalog of TV shows and movies. These videos are ad-free and don’t carry an individual charge, but require a monthly subscription fee.

The new Amazon Video on Demand service is a hybrid of these others. As on iTunes, the TV shows and movies it offers are ad-free and purchased individually, don’t require a subscription, and work on both Windows and the Mac, plus on one type of set-top box. In Amazon’s case, that’s Sony’s Bravia Internet Link, a $299 device that works only with Sony (SNE) TVs.

But, like Hulu and Netflix and unlike Amazon’s older Unbox service, the new Amazon Video on Demand service offers videos via real-time streaming. In many cases, it also allows downloading, iTunes-style, to Windows PCs (but not Macs) and to TiVo devices attached to a TV. The videos can’t be streamed in real time using a TiVo (TIVO).

Amazon’s streaming videos are viewed in any of the major Web browsers and don’t require any special software. I tested the new service on both Windows PCs and Macs, and on a Sony Bravia TV equipped with the $299 adapter box. In my tests, Amazon’s videos looked quite good over a fast Internet connection. However, on a typically lousy hotel Internet connection, the movies were often grainy and kept stuttering.

The new service doesn’t yet offer videos in high definition, something Apple just announced this week it is adding for some TV shows. Amazon says it is working on HD.

Amazon’s user interface for the new service is very nice. All of your purchased videos are available in a library stored on the company’s servers, so you can easily watch them again and again if they are purchased, or resume a partly watched rental. And the service remembers where you stopped watching a video and resumes it at that point, even if you started it on, say, a Dell (DELL), and resumed it on a Mac.

On the downside, the new Amazon service isn’t always simple or consistent. For instance, you can watch only two videos at a time, and not all titles can be either streamed and downloaded, or be either purchased or rented. Most rentals last 24 hours, but some differ.

Selection was OK, but not great. Because of studio policies, many current and recent movie hits aren’t available. There are gaps as well in the TV selection. For example, while iTunes offers the current second season of the excellent “Mad Men” series, Amazon has only the first season.

Prices also can be confusing. Amazon rents most movies for $3.99 and sells them for between $9.99 and $14.99. TV shows generally cost $1.99. But some titles carry different prices, albeit these are often lower.

All in all, Amazon Video on Demand is a good service for people who prefer paying for ad-free TV shows and movies, and is another strong step in the Internet’s rising competition with traditional TV.

Find all of Walt Mossberg’s columns and videos online, free, at the All Things Digital Web site, walt.allthingsd.com. Email him at mossberg@wsj.com.