London is a fantastic city, that's why I keep coming back! Whether it's sports, music, history or food, it's all there in one well connected area. Yes, it's expensive in comparison to other capitals and the British weather may try to dampen your spirits, but once you're past that, you will fall in love with the place. All the clichés are well deserved; West End shows, the magnanimity of it's buildings and more art galleries and museums than you can shake a stick at.
Insider Tip:-Don't over-rely on the tube, if it's less than two stops then you'll enjoy yourself more by walking. -London is DIY friendly so don't bother with tours, most attractions are more fun when explored using your own initiative.