Full of people who were too nervous to leave home but weren't clever enough to get into Nottingham. I have lots of good friends there (for these reasons) and most of them seem happy enough, but they are capable of doing better. It's not even an ex-poly, it was a college of Higher Education and it shows in the teaching.
Facilities are OK, lots of new building being done and plenty of money being thrown at it. There is no campus as such, it is spread out on various sites in the city which are linked by buses. Accommodation is mostly new and OK, but not spectacular. Student housing is plentiful, cheap and grotty.
Derby is supposedly on the up as a city. But Derby Uni is still down at the bottom of the tables for most subjects. It depends on your grades. If you are expecting to do better than, say, Cs and Ds, then I would aim a bit higher.