There is definitely some stigma here of since it is Apple, there must be some kind of catch.
But there is none, I have been buying from iTunes since they opened. It is easier to find stuff and easier to download than Amazon, especially now since they make you download their crappy cloud player app.
Anyway, there is no DRM and hasn't for 3+ years. It is 256kbs AAC and they sound great and can be played on anything. That is all anyone needs to know. Amazon is fine too with their 256kbs mp3 but I find iTunes just makes it simpler.