I can't give much a critique, but I can give an opinion on her for what you want. :) I would say that she would make a good first time horse. Working with her on the mouth will be good for both of you. Many barrel horses you find already started are like that. I like them to be really soft myself.
She should be good for what you need. Starting out there is no real reason to be really worried about flashy. She's sound, experienced, and slower. You've already pointed out most of her issues. I think she's cute, and overall not too bad on conformation.