Well, let me start with the good:
I think the format they went with for this presentation was excellent. Absolutely outstanding, and made most previous E3 presentations look positively archaic by comparison. Excellent job on that.
The bad:
They didn't bring what they needed to bring. Not even slightly. Halo Collection would've been a pleasant surprise had it not been leaked like a month ago; the rest of the stuff was already announced.
Otherwise, MS seem to be investing in niche exclusives. Crackdown sold on the back of being Halo 3 beta access. Phantom Dust was something I had never even heard of until a few weeks ago when it was brought up on these forums. Platinum Games are like the definition of a cult developer - dedicated fanbase, but inherently pretty small.
I'd be interested to see how MS' advertising money leverages these games, but still.
Pushing multi-plats isn't a bad idea. It worked for Sony. But Sony are likely to be able to leverage the performance of multi-plats going forward (an advantage 360 had over PS3).
All in all, I enjoyed the conference. It was a good showing. But I was just expecting MS to laydown the gauntlet for Sony, and instead they just kinda put down a few pieces.