Hi, I've just finished my studies at Swansea University. From my experience, Swansea is a great place to live. Most people are really friendly and inviting. The nightlife is pretty good (Wind Street is particularly infamous for that) and there are lots of amenities in the city centre. I lived in halls in my first year and would say that doing so will give you the best opportunity to make friends and really get to know the university well, as everything is a stone's throw away (very handy for those 9am lectures!). Swansea is full of students and as such, I always felt safe walking home during the early hours after a night out.
Both Campuses are good from what I have seen, can't really comment on Bay Campus as I was based in Singleton Campus. I really enjoyed the atmosphere there. The library was decent and open 24 hours for those late night, last minute deadlines and the student bar (JC's) was great for a morning coffee before lectures or indeed a well earned pint after lectures.
Swansea offers a plethora of societies too, I'm sure there's something for everyone. Uni is ultimately what you make it so, given the opportunity, I would recommend getting involved as much as you can (obviously work permitting!). From what I've found, the teaching (on the whole) is excellent and all my lectures were great to get on with.
The only drawback for me really was the lack of transport links. Obviously, this depends on where you live, but I hail from Manchester so I faced a dreaded, awful and extortionately priced five hour train ride home at the end of each semester. If you're based in the south, or nearby then this won't be much of an issue.
Anyway, that's a snapshot of my experience, hope this helps!