Just been playing with it a bit more - it really is a superb depiction of airspace - the clearest I've seen I reckon. The weather and Notam data is brilliant - nice to see graphical notams again. I hope you get it finished soon as I'd certainly buy a copy.
A few notes (constructive criticism!):
The default airspace filter is <2500 I think. Maybe set this to FL100-125 as this is a realistic maximum that most simple SEPs VFR will transit at?
Make airways default to ON.
Another nice feature would be right click > Insert Way-point here.
It would be good if you could click an airspace item (like a DA) and it brings up the info on it?
(I'm based at EGHS)