don't forget CCTV. mustn't forget the omnipresent CCTV (roads, streets and buildings). also, you aren't allowed to withhold your passwords from police, there's even less police/secret services transparency than in the US of A; your kids will probably be taken away if you discipline them in public or if you go to a doctor with any kind of genital problem (UK children are not allowed to have genital problems).
oh and the sweaty armpits on tube (mmmm yummy), yobs who'll knife you if you complain about their loud music at night (wo'd ya say to mee?) and among the highest rent and property prices in the world. however, it's a good place to live if you're a member of any oppressed minority (race, sexuality, religion) as with so many minorities present nobody gives a shit about that anymore.
and if you happen to speak the most common language of london - polish, your life will be much cheaper (plumbers, carpenters, builders, car servicing, etc). the first thing you should do when you move to london is get a polish friend. i kid you not, they're 100x more useful than your local "citizen's advice bureau".