It'll be cool to do sudokus on the the Kindle, I'd get one just for that alone if it works well. I tend to do about 6-10 a day (with crohn's you need something to do on the loo).
Saying that, a kindle could stop the loo looking like a library, so that's another plus.
Probably my only claim to fame (sad I know) is I can complete a hard level (Times) sudoku in around 2 minutes flat.