I enjoy living in London, but as Travelling Frog mentions,
I think a lot of whether you like living in London or not depends on where you live and work. A long commute from one end of London to the other can kill your day and your wallet, but we're happy walking to work and most everywhere we need to go.
My OH and I work on opposite sides of London -- Him in West London (Zone 3) just where the M4 meets the North Circular, and myself out in Hertfordshire (Zone 8 ) off the A10 about 10 miles outside the M25. To share the burden, we live in Zone 2 North London, where rents are pretty extortionate and our commutes are 50 minutes or 1 hr 15 mins, respectively. Our salaries may be higher, but this is not in proportion with the higher costs of living. At present, I have little to no chance to consider owning my own home, and instead we pay over 40% of our take-home pay just on fixed rent/household bills/commute costs.
Having lived in Manchester, Nottingham, and spent a good amount of time in Leicester, there is no doubt in my mind that we'd be much better off financially if we lived elsewhere in the country (with the rather large assumption that we'd be able to find jobs there).
However, I do enjoy living in such a diverse and exciting city with all the various opportunities it provides. For now, I'm quite content to stay put, but this opinion will likely change significantly within the next 5 years as we inch closer towards settling down/starting a family.