Terminal 1 is hideous, I won't use it unless I really have to, i.e. no other airport has the destination. I find the arrivals experience horrid and embarassing. T2 is OK in that it's spacious, but what was the design ethic, total minimalism? It's like they forgot to design the interior once you go airside, one bar, a Starbucks and little more. It is the most characterless building I know of. T3 isn't bad to be honest.
MAN was a real winner, the SAS Radisson, the Skywalks etc, but seems to have lost a bit of direction.
The airfield bottleneck at Pier C just has to go, and it would be nice if the terminals had shops that weren't so downmarket.