I also have been extremely happy with my kindle. The closest I have to a complaint is the limit on the number of devices that can be authorized for certain books, and even that is normally reasonable. The cloud based reader accessible through a browser also makes that restriction less painful (though I wish they would enable highlighting...)

But I still have concerns about the DRM. Amazon seems extremely stable, but things in tech move fast. Even if Amazon survives, I may eventually want to move to a completely different reader from a company that doesn't exist now, and the DRM will make it hard to take my library with me.

I love the cloud drive player Amazon rolled out for MP3s, but I have it redundantly backed up on 2 harddrives. With the Kindle content I don't have that option.