I finished the Nottingham grad entry course (GEM) in July last year, now working in Sheffield area. Course is 18months pre clinical in Derby, then joining the Nottigham clinical for the last 2 1/2 years. Most of the social stuff in the first year or so was Derby based for the GEM lot, it was all very good but could be slightly cliquey, depending on how much time you wanted to spend with 90 people!
60-70% lived in halls in Derby for 1st year, the rest either privately rented or commuted from Nottigham, trains are very good, some rode, driving a bit of a bind with the a52. After the preclinical a lot of people ended up in Nottingham, but much toing and froing as years went by.
Good course, seemed to be well taught and we all did reasonably well compared with the undergrads on the traditional preclinical section, integration went pretty well - not any real segregation after.
Biking was definitely better when I was living in Derby, some local reasonable stuff and you could get the train to Matlock or drive to the Peak quickly.
Nottingham less so, but as pointed out above advantages of a more formal mtb club etc and a more varied social life and range of people. Derby has been spruced up a lot, I think I preferred it to Nottingham from living/studying in both.