See, that's the part of Van Halen that I really fell for. Most rock songs were about how smokin' HOT some girl was, and how the singer was in LOVE because HOT, and LOVE and HOT! And Dave comes along and says right up front, I ain't talking about love, and you're only semi-good lookin', but here I am, Diamond Dave to the rescue. That was bad ass (though I'll be honest; I didn't give it that level of thought at the time).
I also like the "I been to the edge..." breakdown; the "Gimme a break, Dave..." thing was cool the first 15 times I heard it then sort of became a bump in the road.
I do agree with El Barto about the place of Unchained in the catalogue (it's also from my favorite VH record; that side one is all killer no filler).