You know... I really wish Nintendo would focus on coming out with new GOOD games as opposed to working on new gimmicks. I realize new gimmicks sell, but for god sake I just want a good game for the DS that's not a Zelda, Mario, or Pokemon title...
That little rant aside however, I was still very impressed with the 3DS, and the battery life is no big deal personally, you can plug it in if need be. Unless you're on a plane flight over 4 hours, I personally don't go out and do nothing for over 5 hours and carry a DS with me. I say 3-5 hours is fair considering the 3DS capabilities. Even the iPhone4 playing a 3D game only lasts about 4 hours on full charge so the fact that the 3DS can last up to 5 while generating 3D effects is really good.
I have high hopes for the 3DS but I want to see some good games coming out as well. Not just another gimmick.