Well the research done by the university's history dept is certainly of a high standard (
here) and on a par with all the other unis you've applied to. The non-RAE league tables show a similar trend, look it up yourself. I'm a bit too old for angsting over league tables anyway, so I shall simplify this for you: if you like QMUL then come here, if not, don't. At the end of the day, a University of London degree has never done anyone any harm so that should allay your worries about prestige.
The usual employability stats, QMUL being top 10 for starting salaries etc here:
http://www.qmul.ac.uk/undergraduate/whyqm/career/index.htmlSeriously though, did you actually bother to read the prospectus before applying?
Well since you're visiting in less than a fortnight, you can make up your own mind. The area was once quite poor...now it's pretty much a hotspot for middle class white indie students. Not just from QMUL either, lots of UCL, KCL etc students live in Mile End as it's cheap and the transport links are good.
Come with an open mind, see what you think. If you like London, you should like QMUL, simple as.
I can only offer you my perspective as a QMUL graduate that it's an amazing place to study and I'd give it five stars any day of the week. You're in a fortunate position that all the universities you've applied to are excellent...so just pick the one you like the most and go there. It's really as simple as that.
I haven't negged you, but perhaps (understandably) people expected you to do a bit more research about a uni you've applied to. These are some pretty basic questions you're looking for answers to...how could you have not thought about this all several months ago?