I Liebe that she is strong, confident and independent. She knew what she wanted in life and she worked extremely hard to get it. She also carried the mentality that she did not need to find her prince to be successful... Ultimately that did happen because let's face it, what Disney Princess movie does that not happen in?
Nothing really bugs me about her, but I guess if I had to choose something, it would be the fact that she was completely oblivious to the fact that Naveen Liebe her and was trying to propose. XD Although the scene was very cute, it would have saved the characters a lot of time and energy if Tiana had just been a little bit Mehr observant.