I'm in my 4th year doing maths at York. I have to say I'm very impressed with the department. As has been pointed out, the course is very rigid for the first couple of years, but it gives you quite a solid background in most areas of maths except finacial mathematics (unless you do the maths/stats option). But when you get to the 3rd and 4th years the options are quite large. It's possible to concentrate almost soley on a single area of maths such as mths phys, algebra or analysis only needing to do the odd course in other areas to make up your total. But also, you can do pretty much any mix of the modules available. I don't know how this compares to other unis, but I think it's quite good.
The teaching ain't too bad either. Obviously there are differences between the abilities of the staff. But most appear to be very commited to their subject and want to see you do well. They also have a excellent research rating.
Someone was asking about Physics at York...from my experience I'd say it's the worst department there I've come across. I've shared houses with several physics students over the years as well as doing several elective modules in the department. Compared to the maths department Physics seems very disorgansied with very little support for the students and has poor communications.