For a First World country (and currently the fourth largest economy in the world), the UK's airports are, by and large, an absolute discgrace.
The majors (LHR, LGW and MAN for example) are rundown and dirty. Airbridges and corridors are littered and the filfth is ingrained. Carpets are filthy (why, oh why fit carpets in an airport?).
I get the impression that those airports operated by the BAA - this excludes MAN - are more interested in promoting retail activities rather than improving infrastructure.
MAN has really gone down; 10 years ago it was great. Last time I flew in there (last year), I felt disgusted enough to call the airport to complain about filthy toilets and an arrivals area littered with cigarette ends. The airport was cleaner when they employed their own cleaning staff.
NCL is not too bad, to be fair.
None of our airports rate alongside AMS, BRU, HEL, CPH, ARN to name a few I've used recently. Even BWN is better for its size and location.