I've played the demo and will definitely buy the full game, probably through Steam when it is on there. I'm enjoying the graphics and new features such as being able to customize my planes. A few things that I would like to see in a patch (assuming they have not already been added are):

A stock market.

Being able to improve cabin equipment faster. I may be missing something, but I could not find a way to make several improvements in one go.

More options for creating flightplans. It would be convenient to be able to choose exactly what to repeat instead of only being able to repeat x days.

I concur on the faster-cabin-upgrades and definitely the easier-flight-plan copying. Right now it's slow and tedious.
Personally I never really thought the stock-market added much to the game though, so it's an omission I can live with.