I think Phileas has got it just about right.
My recent personal experience is of Norwich (because I work there).
It has suffered tremendously firstly because, after the owners investing £ms in various facilities and perhaps being "rather optomistic" about potential routes and pitching into markets we couldn't possibly compete with, along came the recession, then when things looked as though they were getting back on track, along came the ash clouds which hit them for more money than you could ever imagine.
The former, to a certain extent, could have been predicted but never the effect of the latter.
However, despite the fact that sheduled and charter traffic is nothing like it used to be, things are slowly getting better and helicopter traffic (North Sea) is doing very well and will get even better when a new operator moves in in May 2011.
New airport management has lead to a more pragmatic approach and there is significant private investment in new hangarage and FBO facilities leading to new customers.
I've worked in aviation for over 30 years and I've always found that usually the first thing to suffer in a recession is aviation, it's also the first to emerge from it, but failure to learn is the one thing that really will screw you.