The only downfall about getting these from Amazon is the fact you can't download them to your computer. If Amazon loses their agreement with the studio, your video will no longer be available to play (unless they get the rights back at a later date).
With iTunes I can download it and keep the copy on my computer or back it up to a disc. Yes it still has DRM, but I can watch it whenever I want to and not have to worry whether or not I can stream it. I like renting & streaming Prime Videos from Amazon, but not big on purchasing them due to this.

EDIT: You can download them, but ONLY on a PC. You can't download them to a Mac or Linux computer.
So if you are a Mac user, it's better to purchase (not rent) from iTunes.

Nonesense. You can download the movies to your computer or other device to watch anytime without needing to be connected to the internet.

From the help pages:

How can I download a video?

We recommend streaming Amazon Instant Video titles so you can watch your video immediately. To download an Amazon Instant Video to Kindle Fire, click Download after purchase and your video will be stored in your device Library. You can also download videos you own from Your Video Library at any time.

What's the difference between streaming and downloading?

Streaming Amazon Instant Video allows you to watch a video through your web browser or compatible Internet connected TV, Blu-ray player or set-top-box. Downloading an Amazon Instant Video allows you to watch a video on your Kindle Fire or PC computer without an Internet connection

http://www.amazon.com/gp/help/customer/display.html?ie=UTF8&nodeId=3757

A Kindle Fire is not my computer. You can only Stream on a computer, not download. At least you can't on a Mac.

[Deleted by the author on Feb 24, 2013 12:56:04 AM PST]

J. Nichols,

I can stream on my computer, my TV and my Fire. I can download to my computer and/or any external storage device, then watch on my computer or my TV. I store movies on an external 3TB device. However, most movies I keep in Amazon's Cloud and stream via my Rokus.

Has anyone had problems with the Roku and amazon streaming long movies?

Same here! I stream on my computer, TV and fire as well. I, too, can download to my computer and external storage device. But I guess there is always someone whining. You would think mac users would be used to being handicapped with things such as this. Stick with itunes I guess! Or get a PC ;)

Wildcat,

I never have streaming problems with any of my Rokus. I stream movies and TV all the time, including long movies.

Or you could just buy the PHYSICAL COPY -- either DVD or Blu-Ray -- and actually OWN the item you purchased and be able to LOAN said item to friends. If they like it more than you? You could SELL it to them LEGALLY under the law known as RIGHT TO FIRST SALE. Or, you could waste your money RENTING a copy from AMAZON, which is EXACTLY what you're doing, if you choose to download ANY of these films. Convenient ... yes. But is giving your right to OWN a movie up worth the sacrifice?

If it has DRM, of any sort, it's ANTI-CONSUMER and not worth your time. Can any of us imagine a day when we bought a book and would be arrested for lending it to our best friend?

What happens when Amazon's Cloud goes away, or Amazon loses the digital rights to allow content you bought in their Cloud? Read the Terms of Use. You may be surprised.

I'll stick with a hard copy (blueray or DVD) that I can actually own and hold in my hand, not to mention the better picture quality.

Most movies are not worth watching even once let alone a second time. Movies that are worth watching often have special material on the blu ray and these are not available for online viewing. Save your money and build a decent, small movie collection on blu ray. Watch when you want not when an online source, your ISP and a PC are available at the same time.

Amazon streaming service works quite well. A nice feature is if you're interrupted (even turn off your TV), Amazon's streaming service remembers exactly where you left off, and you just hit "RESUME" to continue watching at a later time.

Just in case anyone likes "Closed Captioning"/subtitles-- it's NOT an available option on streaming.

[Deleted by the author on Feb 24, 2013 5:15:24 AM PST]

I have been renting Criterion movies via Amazon streaming at $3.99 each, so to be able to purchase for a couple dollars more is a good deal. Criterion blu-rays are expensive to purchase and generally difficult to rent at Netflix (impossible at Redbox). You can tell the Criterion titles in this deal with the small C logo in the top left corner. I really enjoyed The Red Shoes [HD] for instance.

There is no guarantee that Amazon's "video library" or cloud service will exist in the future. This offer explicitly states that your purchase will be stored in Amazon's "video library" and then you will watch by accessing the library. Technology changes and Amazon cannot be expected to maintain backwards compatibility forever. If backwards compatibility is lost, Amazon, even if it continues to exist, is unlikely to refund your money.

The quality of streamed movies is certainly less than from a hard copy. What is more, many people's streamed experience is poor because of slower download speeds.

I used to be one of the people who thought it was a mistake to not buy a physical copy. Then i was bored one day and bought something here (it was a silly movie, Ted. I LOVE that it is always there for me via streaming. I have watched it on my kindle fire, I have watched it all over the house on different rokus...and I never have to worry about where the dvd is, or carrying it around. We used to have another apartment for my husband's work, and we could watch it when we were there. It is very convenient.

I don't know how to download to my computer...mostly because I really don't care to. I am not going to watch it there anyway. It isn't like these things are 50 bucks and I will lose big money if they go away. If it is something I really enjoy, I do still usually lean toward a "real" copy. I sort of wish that the streaming version was free (or really cheap) with the physical purchase. Sometimes the dvds/blu-rays come with a "digital copy" but I don't usually use them because I don't know what to do with them after they are on my computer. And they EXPIRE (which is crappy) if you don't use your "code" fast enough.

@ Perry Denton You can stream the Criterion collection if you have Hulu Plus, and some are available on Hulu. For the price of two rentals, you may want to consider it.

There are some great movies in this bunch. Are there any that are not available via Netflix? I'm trying not to buy hard copies of DVDs anymore to save on space. Netflix has the Clint Eastwood version of "Birdman of Alcatraz" but not the Burt Lancaster one.

Not all the videos are coming up as $5.99 in HD. I looked up both Moonstruck and West Side Story and they both come up as $8.99 in HD. Am I misunderstanding this offer? Or has Amazon not double checked to make sure they changed the prices on all the offers? (And after I post this will they change the price, so when people look, they will think I am nuts? :) )

For Criterion Collection movies you may want to consider a Hulu Plus subscription. I haven't done it yet, but I keep thinking about it. They don't have every Criterion release, but they've got a ton of them.

http://www.hulu.com/movies/criterion

Not only are prices wrong, but these are coming up as rentals for 24 hours instead of purchases. They can't get this right at all.

Thanks, Craig. "The Tin Drum" is on Hulu+. I watched that movie when it first came out. What a masterpiece.