LGW is very nice. Comparable to all the nice airports in the US at least (LAX, JFK, etc.).
The terminal looked newly rennovated in mid-January. The only bad part was the 500,000 mile/kilometer hike to Delta's gates.
As for Gatwick Express, I thought it was about the same as the New York City subway.
Pan Am:The World's Most Experienced Airline - P(oor) S(ailor's) A(irline): San Diego's Hometown Airline-Catch Our Smile!