There is an option to publish without DRM, but the consensus of advice I got was that Amazon DRM was not intrusive and was worth it for the author.
I generally dislike DRM, but it can be done without being a pain, and Amazon seems to come close to that.
The format lock-down is the biggest issue that I can see, though with the ease of use and free availability of kindle software, it is, as I said, a minor issue to me.
As for Amazon's DRM, I doubt Amazon is going to start removing books that people have bought; they tried that once (with books by Orwell, of all things) and it hurt their repuation enough that I don't see a repeat being likely.
Of course if Amazon goes out of buisness, I could be eating my words with salt and cursing their DRM.
Meanwhile, to those who refuse to by a format-locked book with DRM, I understand your point of view, but, obviously, I'd be glad of your making an exception for my book...
