Irihi
Welcome to the World
As far as Vaan goes I personally liked him, I do think that his personality could have been worked on a little more, and although people call him useless as I've said so many times before he's only useless if you make him useless. Trust me, I keep him in my main party and believe it or not he's come in handy and gotten me out of a lot of tough spots more then once, and Ashe is at a higher level then him. I think his brother being wrongly killed was motive enough for him, I'd want revenge too if someone went and killed my brother.
In all honesty he's got a good stand in the story somewhat, he's partial comic relief and he's there to help along the way, make the story move. Everything is connected, like in every final fantasy game before XII, just look at it for a moment, and not only is Vaan really going after revenge for just his brother but along the way you can tell he starts to really concern himself with saving his home as well as helping Ashe. So before you rule him out too quick because of how he lacked in personality somewhat, sit down and think, is he really as useless as I think he is?
In all honesty he's got a good stand in the story somewhat, he's partial comic relief and he's there to help along the way, make the story move. Everything is connected, like in every final fantasy game before XII, just look at it for a moment, and not only is Vaan really going after revenge for just his brother but along the way you can tell he starts to really concern himself with saving his home as well as helping Ashe. So before you rule him out too quick because of how he lacked in personality somewhat, sit down and think, is he really as useless as I think he is?
And like Irihi had said it's not weather or not you liked his personality or not he was apart of the game and he had a purpose which was to get revenge. I also try and make my character's equal and switch them out so everyone gets a chance so as far as his skills in battle he was just as equal as anyone else was. To me, it's all about your stragety and technique. As far as him being the main character not so sure but overall, I say he was OK 



