I'm just finishing my game development course and bought KSP for christmas after hearing nothing but good things about it after watching an episode of Good Game (a games review show on Australian TV). Loving it so far.
Yeah, so it's not as heavy on the physics as Orbiter but that'd make it a great as a teaching tool as well as a game, and the whole idea of controlling your own space program from any perspective is just pure epicness. I can be an engineer, pilot, astronaut, project manager, flight director, etc. Not many games can pull that off.
Also, I liked the nod given to Orbiter with the Ravenspear - very nice touch.
The only thing that I don't like so far is the somewhat pixelated text of the options in the menus. Turn those into interactive buttons and you're set.
To you and the KSP dev team: Whatever it is you're doing, keep it up.