Love it! The writing is brilliant. It can be slightly hit-and-miss, but the good far outweighs the bad.
It's odd, though: the first time I watched it I didn't like it at all. A few months later I re-visited, because David Mitchell is amazing on panel shows, and found I liked it very much. Literally laugh-out-loud moments. Now I'm starting to tire of it again.
Regardless, it's loads better than any sitcom we have here in America.