I'm just going to reiterate again, because there seems to be a prevailing theme that UCSD is "gunnerish". I don't know what these "sources" are, but here is an opinion from a current medical student who loves it at UCSD.
We do admit to the fact that UCSD used to be a very competitive school. This was mainly due to our previous administration. However, as of Dean Kelly, UCSD has become a very sociable and welcoming environment. Just in these last two months: we've had a class Vegas trip and a class skiing trip at Mammoth...not to mention all the smaller social events that we have. All of these events that we have come about through the use of our forums. We actually utilize our forums all the time, because we like to share things with each other. If you just look at our forums, you will see all sorts of study guides that we create for each other and all sorts of social things we invite each other to.
Yes, we do study a lot. But we also have a lot of fun. The part about studying comes from the fact that we have frequent exams. Some may hate this, some may like it. I personally find it useful, because without it...I wouldn't have much motivation. It helps to keep me on top of things. Yes, life gets stressful at times, but it should anywhere you go.
The fact remains, however, that UCSD med students do everything they can to help welcome incoming students and applicants. We take out a lot of time to give tours and answer questions. We wouldn't be doing this if we didn't love our school and if we couldn't afford the time.
I do love UCSD, but I love my classmates even more. I have never once felt the sting of competition. I have felt extremely at home here. Dean Kelly knows every student by name, and it is the support of the administration and there attention to detail, that has made our class so extremely social and cohesive.