Mitt Romney and Rick Perry have something in common as campaigners: they are both much better on offense than defense. Perry, as both New Guy and Frontrunner, is naturally getting targeted these days, not just by Mitt but also by the various candidates striving for relevance. I thought Perry was so-so handling that in last night's debate; not good, but not bad enough to send people fleeing for the exits. So, in the short term, Romney gets a slight gain in piercing the Perry image, but Perry gets one debate closer -- and more experienced -- so I'd say it's a wash.
Michele Bachmann did a nice job re-elevating herself from the Santorum-Gingrich-Cain level, which keeps her relevant; she'll still need a lot to really get into the Romney-Perry tier, and I don't see it happening. On the other hand, Ron Paul continues to demonstrate what I've said all along: that if he ever starts polling high enough to worry the establishment, they'll start treating him like a real candidate and expose how out-of-whack he is. It won't eliminate his core following, but it should limit his appeal -- which should be good for Perry.
As for Jon Hunstman... let's see.... I guess we learned that his supporter is a Nirvana fan. (He gave an odd, awkward, and technically inaccurate shoutout to Kurt Cobain.)