Here's a tweet from BBC Learning English which raises an interesting grammar question. In fact, I don't agree with the assertion that 'I am loving living in London' is 'informal usage'. Surely it depends on the context. For example, if someone has just moved to London (from somewhere less exciting), I can quite imagine that they would say 'I'm loving living in London.', whereas 'I love living in London' would suggest that the speaker has lived there for some time. It just goes to show that where grammar rules are concerned, context is everything.