I was at Sheffield last year, although I've now switched course and uni.
Sheffield is a very good city for students. With it having 2 universities, both around 30,000 students each, the place is swarming with them, and the city's businesses take full advantage with plenty of student offers and deals.
If clubbing is your thing, you'll never be bored. There are events on every single night of the week.
There are plenty of nice parks/gardens to chill out in on nice days too.
The only thing I would warn you about is that Sheffield is the hilliest place ever! Just walking to your lectures and back can be knackering!