At a minimum, you need to check out the "Death Heat Maps" at the bottom of this page. The rest of the data is pretty interesting too, and really shows how balanced all the characters are. I think based on the stats, the Engineer is slightly behind the rest, and I'm surprised the Demoman and Pyro aren't 'higher'.
The other really interesting piece is the stat right above the Death Heat maps -- Round win % per team per map. I don't understand how a map like ctf_2fort or cp_well has such a low red win percentage when it is basically a symmetrical map.
I hope Valve comes out with a few more maps... they've done a very good job of creating balanced maps that require quite a bit of strategy and coordination to do well in.