Just to second henryt - doing well in the Norrington Table doesn't make Merton a bad place to be. Some people at other colleges seem to assume that Merton's finals results could only have been achieved either by everyone there being really boring and/or competetive to start off with, or by college cracking the whip until we all submit to life as academic hermits.
In fact, lots of people at Merton didn't know about its reputation before they applied, and chose it for totally arbitrary reasons like good food or location (I have to admit I was slightly swayed by the cobbles...) - so none of them arrive with a burning desire to tread the competition underfoot and give up life outside the library. More than one person in my year failed their Mods/Prelims, and college let them resit without any problem. I can't speak for every subject, but the English tutors never put pressure on us about results, and were always understanding if people had problems with work.
The only evidence I saw of a push for good exam results was the number of revision classes we were given in Trinity (I am a finalist, currently having a mental breakdown waiting for results to come out). They were all optional though, and we were very very grateful that we had so much help from our tutors when we wanted it. What's more, they were constantly telling us to make sure we took time off to relax and have fun - somehow, being advised to go for a 'jolly' walk to the Trout for lunch because it was such a nice day, 3 days before our first exam, didn't strike me as fitting with the Merton stereotype. But that's not really surprising, because I've always thought the stereotype was rubbish.
Also, the success rate of applicants to Merton is no different to that at any other college - only Magdalen, that I know of, has significantly more applicants per place than anywhere else.
Henry, I suppose you have guessed who I am pretty easily...