Back in August I reviewed Amazon's Unbox Video Store and my conclusion was: great service, unworkably bad format (it doesn't even work if you uninstall the downloader?!). A few months later I tried out the Amazon MP3 store, and now they've got some more big-label buy-in, I'm finally getting around to writing a review. Amazon has learned from that mistake (or rather, has finally managed to teach the dinosaurs at the record companies), and Amazon's MP3 store is exactly what it says on the tin: MP3s, without any restrictions or DRM, at a very respectable 256kbps.
The pricing is also well-researched, as you'd expect from Amazon. Individual tracks are 99cents (still following the very profitable law of small numbers), but full albums are $5-10 -- I picked up a double-disc set of Elton John's greatest hits* for a very respectable $15 and continued to bulk out my oldies with Led Zeppelin for $13, or roughly 50 cents a song. Now that's a price I can get behind. That feels like what a song is really worth, and given Amazon's levels of market research it's probably for exactly that reason they priced it like that.
Technically the system is seamless: you download the MP3 Downloader software, and when you click the "buy album button" a little package file is downloaded to that application. It then downloads the files in the background according to your settings, and optionally adds them to iTunes (or Windows Media Player, if you're a masochist of some kind). No muss, no fuss, and importantly: no DRM. The ID3 tags contain a clearly-visible "Amazon.Com Song ID", but this looks like simple labelling, not any kind of tracking attempt, since ID3 tags are easy to edit (you could scrub just the Amazon IDs from all your songs in iTunes in about 4 clicks).
In summary: it has the Seldo Seal Of Approval™: go get 'em! I'm already impulse-buying at 99 cents, god help me....
* And how long until the whole idea of a "double disc" set is just a quaint anachronism like the EP?