I'm actually glad this topic is getting some action! And I like to hear what other members have to say! As much as I hate to say it, I was worse than I am now - and that's saying something - when I played AP TF, so there's a chance I mis-used him back then as far as damage output goes. However, the problem still remains that he's too weak early game no matter which direction you're going - whether doran's ring or doran's blade...getting anything else meaning you have 450 health xD - Twisted Fate is incredibly low powered from 1 to 6, decent ENOUGH to get by with assisting after the first build item, and grows from there.
Since TF is free this week, I'd definitely like to see that stats on how many people play him, play him and don't play him again afterward, and play him and keep playing him. So far, I haven't see one Twisted Fate show up in any of the normal games I've played, and I fear it's because he's got a bad rap for being a bad champion when that simply isn't the case.