Ok, so here's part two of my "I just got a 360 and here's what I think"...
Xbox live (not specifically the online mulitplayer gaming) but the whole enchilada is really, really cool. I downloaded a whole bunch of demos from arcade that look really interesting. I ran out of time so I didn't get a chance to buy points and unlock a couple of them.
I downloaded a few trailers, clips, full game demos (dirt) and generally just checked everything out. Bottom line is that if "online experience" was a category in every review of the overall console market, the 360 get's a 9/10. My only beef is that some of the content is rather expensive and I don't care for the points pricing scheme. I would prefer 1 point or 100 points = $1 so I'm not always having to do math in my head to determine the cost, but I suspect that's another money grab. Outside of that, online is phenomenal.
I have not experienced PS3's online universe, but assuming they want to outdo MS in this area, they need to bring their A-game because MS's is top notch.