I'm really excited about Team Builder, but I can unfortunately say without qualification that without it, I would have skipped NCAA 10.
The fact is, for all the little improvements being brought over from Madden, the two game changers (overall game speed (pass speed in particular... I can live with NCAA playing faster than real life, but the pass velocity is otherworldly and that has a huge effect on realism) and Pro-Tak) were not, and for that reason, NCAA will not be the "Sim" Madden is. Another thing is that Madden will surpass NCAA by a long, long ways in the presentation department this year, and the atmosphere gap will be closed significantly.
In other words, the only real reason for me to purchase NCAA 10 is this mode and to fill time between July and August, and this is despite the fact that I prefer college football.
It's funny... every really big improvement in NCAA is a result of Madden. The only thing they've done on their own is redoing pursuit angles. Otherwise, the pockets are a branch of Madden's pro-tak, Team Builder was originally developed by Ian Cummings and others for Madden before legal issues persuaded them to limit it to NCAA, branching animations in the running game first appeared in Madden 09.
Really makes you wonder what the NCAA dev team are even doing.