You do mean the marginal tax rate, right? Not the average tax rate. To be taxed @ 42% (average) in Germany your income would have to be way north of 300k€ [1]. With that kind of income, your social security (health, unemployment, pension) would already be somewhere below 10% so nothing to complain about, really, given the benefits (yes, I know the benefits are no longer what they never used to be).

Add to that the absurd housing costs in, say, London, and things don't look too shabby for Berlin. Although you need to be tolerant towards the locals. I can understand some people having problems with that nonchalant "don't care if you care because, you know, I don't care" attitude that sometimes shows. But if you're capable of letting the occasional inflammatory/stupid remark slide, these guys and gals are quite nice. (Protip: This ability is great to have pretty much anywhere. Hanlon's Razor, anyone?)

To me, London is great to spend a few days of vacation. The atmosphere, the people, British humour, all great. Still, I never felt the urge to permanently move there to work. Too crowded, hard to get a decent flat... I guess it's not always just the money.

[1] https://en.wikipedia.org/wiki/Taxation_in_Germany