That's really a surprise. Broadcom is cemented in my mind as one of the hardest companies to get even basic datasheets out of. I know the saying is "don't look a gift horse in the mouth", but could it be that their graphics cores are not competitive in pure technical capabilities, so they've decided to compete on open-ness? I'm not really involved in that area of hardware/software.
Nope (though note, I'm biased for several reasons). In terms of performance per unit area and performance per Watt, VideoCore IV is about as good as you're going to get. There are chips with higher performance GPUs out there, but they get there by brute force: throwing area (and therefore cost) and/or power at the problem.