I messed around with a Kindle not long ago, I really liked the display... they did a good job there....
But I felt like the interface was total crap. I dont have an iPad, and doubt I will be getting one withing the next year, but I will say the interface for iPad is about 100x better... if I were going to get an eBook reader I would strongly consider Kindle but likely end up on iPad.... for several reasons (interface, capability, commonality with my iPhone)... I will admit I am pretty picky / spoiled when it comes to interfaces though...