I did group therapy when I was inpatient and when I was in partial. The groups were mainly focused on CBT and DBT skills. There were some process groups which kind of felt like complaining sessions.
I don't think I really got too much out of it group therapy. It is very generalized, and even if you are open to pouring out your problems to strangers, they don't allow too much of that anyway.
In a lot of ways it felt more like a class than a therapy session.
Ultimately, it can't hurt if you can learn from other people's experiences and use the coping skills they teach.
I suggest you give it a try and see if you think it will be helpful.
best of luck to you....