I work up north not in London, but I've been down a few times on business and there's some similarities between Leeds and London.

Generalisation time! Culturally it's probably like most larger cities, outside people just want to go from A to B and as it's quite busy in commute times they'll probably try to push through you which can be stressful. Unfriendly is what some people would call it. Service at some shops/restaurants is poor because they don't give much of a shit as they'll get a lot of footfall regardless, having said that you have an unimaginable number of options available to you so you can learn which ones are good. Combine these two things with the sheer number of beggars around stations targeting tourists and blocking your path and you can find yourself having a pretty shitty time. There are a lot of benefits of being in a big city too though.

Companies will vary greatly, but despite offices in London being massively expensive I see some companies really push the boat out in setting up nice office environments and take care of their staff. My experience with programmers at companies I've met is that they're very chilled, down to earth, and friendly. There's probably a lot of companies that pack people into dingy basements too but they're everywhere.

As for recruiters they charge around £5,000 for whoever they can get, and deal with targets and KPIs all day. It's sales at an extreme and highly stressful, attracting some very cocky personalities. There are some who can be very helpful, some who will call you all the time, some who won't respond once they know they won't get money from you, some who try to hard sell everything, and some who will twist words and lie. There will always be another recruiter or company, so just look out for yourself and try to know exactly what you want when dealing with them.