So the main argument I agree with against caverns is the one posted a while back:

Caverns doesn't let you play lackey turn 0
Caverns doesn't let you play vial turn 0

This means you're still behind the curve in terms of lackey swinging and vial getting counters. Against a lot of decks, especially combo, this is the biggest deal. Granted, I'm not arguing caverns is bad, but it's *not* like going first, unless they're dumb enough to wasteland you :-P. Control decks will realize you went down a card and just try to counter your threats most of the time.