I can't give personal experience, but from previous threads the following is apparent:
* LSE cares about research rankings, and some students feel they cannot approach teachers or do not receive adequate feedback
* Living in London restricts SOME aspects of social life due to financial cost - people feel they don't have the same experience as at other, more "sociable" universities
* The courses are very intensive - high amounts of workload and stress are applied to students, which leads to the university's prestige
There are other reasons, but cost, stress and the lack of feedback tend to be the most obvious.
However, these tend to vary on an individual basis.
* Though contact hours are limited, those who actively seek out advice and teachers, using their own time, will obviously gain more than those who don't.
* Those who don't go out upon the town each night will obviously save money. LSESU hold many cheap events for students to enjoy
* Granted, not much will detract from the intensity of the course. Keeping on top of work, however, will reduce stress significantly
Overall, I think everyone's experience varies individually, and therefore it is what one makes of it. I wouldn't worry about it too much - I personally am not!!