Oxford's books are variable - fabulous in places, not so great in others. I've heard Bristol is the same. I guess this is inevitable when you have lots of different people writing on different subjects. Heaven knows why they don't hire a proper technical writer.
Anyways, what I would say on Oxford's books is that they're currently being re-written, and there are syllabus changes coming in, so unless you're absolutely desperate to get started it would be worth hanging on for a bit. I think the new books will be superb. Anyway, have a word and see how the timescales are looking for these changes.