i've actually found the self-deprecation schtick a little much at this point. on top of that, now that you mention it, his interviews are, with increasing frequency, prone to getting super-off-track by his antics and hijinks.
still, i'm a pretty big Conan fan, at the very least, because all other late night talk shows are pretty lame in comparison. Leno is obviously Leno, Dave's just kind of old and grumpy now, Kilborn is just okay, and Kimmel can be interesting to watch, but i'd be surprised if he's still at it in two years.
here's a pretty good article that was recently written that's worth reading: