Given the problems you've described you are likely to be more comfortable after the surgery. The experience could differ depending on whether the J-pouch will be removed vs. left in place. Sometimes the anus is sewn shut ("Barbie-butt"), and sometimes not. You should be clear on what's planned before the surgery.
Pouch removal is sometimes a complex surgery, since the pouch can become attached to adjacent organs. Getting rid of a failed pouch seems to get good results, though, if done by an experienced surgeon.