Niggles so far, the scroll buttons on both the left and right side (to support left and right handed use I assume) mean I do accidentally scroll in crowded conditions, but I'm already compensating. I'm also disappointed that some books are region only, for example you can get Fighting Fantasy kindle books in the US but not in the UK it seems. Also, smaller publishers seem to not on there yet - Black Library I'm looking at you, trashy 40K novels are ideal for the Kindle. (Actually not all the 40K books are trashy, but you know what I mean). Also, Freya managed to crash it in about 2 minutes but zooming and changing the font on a *cough* TSR PDF I uploaded - It's ok, I have an original B4 at home.
But reading a Kindle formatted book is a very pleasant experience, especially when you're somewhere book unfriendly. I'm a hoarder and I do feel a sense of guilt about not adding the mound of books that our little flat cannot contain. I also wish that Amazon did some sort of scheme whereby you got free or cheap versions of books you previously bought as paper.