I use a release b/c I've got a short ATA bow. The pros of using a release are that you get extremely consistent string release each time, there's less torque and "string-roll", and it's a little easier to pull high-poundage bows. Cons (as far as I'm concerned) are that it's one more thing to keep up with and make sure it's correctly attached to the string/d-loop. Also, I always liked being able to "feel" things out, to have flesh on the bow-string. The largest downside to fingers (if you want to call it a downside) I guess is that you have to practice harder and longer to maintain good form and consistent release, and of course you have to find a consistent style to release in the first place.
However, as much as I like shooting fingers, my bow is so short that it hurst like crap and my shots are real inconsistent b/c it is not very forgiving, so I went release. My next compound will be a long ATA, like 45" so I can shoot fingers. I don't know exactly what a good ATA cutoff point would be to consider switching to release, maybe 38-40". I can shoot my dad's 40" with fingers relatively well (better than my own bow anyway, which is 33").