Swansea is great. I lived there for years and studied at the university for a year. I've studied at a few universities and found it no better or no worse than the others, although my experience was in 1996 so a bit out of date!
There are areas of the city your DD should avoid although nowhere in the city is particularly bad in comparison with other cities.
Swansea nightlife is very contained and centred around one or two streets so is pretty fun; there is nothing quite like Wind Street!
The beaches are amazing, and if she is lucky she may even get a view of the sea every day. I really miss that.
If she likes shopping then Swansea won't excite her although her money will go further than in other places!
If you have any other questions I'd be happy to answer them. I get back to Swansea every few months or so.