One of my husband's co-workers had shoulder surgery last fall - he's back to mountain biking again and I know he is doing really well - I'll have to ask for some more specific details though.
What you're saying sounds like what I ran into with researching knee surgery. You end up hearing horror stories about people who wish they'd never had surgery (people with problems are the ones most likely to speak up, and people retell those stories, so you hear a disproportionate amount of them), but a good number of the horror stories are from people who were seriously out of shape to begin with or disregarded their rehab/physical therapy protocols, or re-injured it before it healed, or something like that. Make sure you get the whole story before you let it dissuade you from doing it.
I expected to be truly miserable with the sitting around too, but that part wasn't as bad as I expected. You're drugged for the first few days when you can barely do anything, and then you're constantly doing stretching and muscle building exercises after that. Especially when you really want to get back to sports, you have the motivation to work hard at PT. Overall it can end up being a good thing - all the time at the gym can get you into better shape all around, and you learn a lot about your body - how to keep strong and prevent future injuries.