I've never shot a thumbhole stock so I'm only relating info I've heard from others;
Pro, the thumbhole stock alows your hand to take some of the recoil.
Con, a thumbhole makes it more difficult to operate the bolt quickly (if that's a concern).
I sure do like the feel of every one I have ever handled. They put my hand in a more comfortable position than a standard pistol grip stock. I fully plan on putting one on one of my guns in the future.
Genises 27-3: Now therefore take, I pray thee, thy weapons, thy quiver and thy bow, and go out to the field, and take me some venison...