Admittedly not the same subject as yours, but I suspect the same would apply for most subjects. I studied Philosophy. The tutors were excellent, both in terms of their academic standing and their willingness to support their students. Some of them were willing to provide extra support by offering more tutorials than they were required to do by the department.
As for comparisons with Oxbridge: the dept itself is certainly comparable. At the time I was there, the dept of philosophy at Cambridge was of pretty much the same strength. Oxford was, and remains, one of the strongest depts in the world, up there with Princeton. St.Andrews doesn't offer one-to-one tutorials (although I have, on the odd occasion, had them), but then Oxford and Cambridge aren't in the position to offer these as often.
I suspect that, in general, St.Andrews is Oxbridge-esque in terms of the architecture, the standing of the academics and the prospects of its graduates (particularly in terms of further academic study: many go on to study at the Ivy leagues and Oxbridge etc.). However, sometimes i questioned the commitment of some of the undergraduates in a way that i imagine (or hope) wouldn't be the case with Oxbridge undergraduates. Its smallness, as many people on this forum have said, is a big difference. But, somehow, it wasn't ever a problem whilst I was there. If you're enjoying your course, have good friends around you (with whom there is a social scene to share!), then St.Andrews' size isn't a problem. It was a pleasure to live there.