Congrats. Yeah, don't rush into any decisions and think "CAMBRIDGE IS THE BEST!" until you've visited both and feel something for one of them. It could be right for you, since you've got the grades to apply, but if you feel it isn't then don't.
I know one person who is doing it and she loves it. She said that she did it at A-Level, and that it's just more detailed from that really. She told me that it was hard work (as is any degree!), but that you won't really get bored of it.
Also, like I said, until the end of the third week of lectures, you can change courses here, so don't worry if you secretly hate it if you come here, you can change! I know people who've dramatically changed from Philosophy to Law!
I've not heard any criticism from teaching, and if you do, the university do termly evaluations, so you can basically fill out an online evaluation (anonymous), and fill out what you love/hate, and they change things and so on accordingly.