We just bought this innotab 2 and love it. We had the fist one, but my little boy kept dropping it so it no longer worked properly. I would wait until she is 4 or so to get it, it didn't make it long at our house due to slippery fingers! Hopefully now that he is 5 this new one will fare better. Good luck!!
My 2yr old daughter is insane over her Innotab 2 and so is her 6yr old sister..lol so I would say from my experience it can last till shes 6 or older they have games for 6-7 yr olds so as she grows you can get the more advanced game.