I would be disappointed since there seems to be a lot of unfinished features partially built into the game. I feel like with the currents part and mods available, the ship building aspect is complete. Although some tweaks would be appreciated to ASAS and auto RCS balancing, I think those are minor issues that can be fixed in patches or mods... However, I would really like to see some sort of finance management system where money, fuel price and construction cost become an extra problem Kerbals need to solve. Tied to this is the career. I don't need a career mode to enjoy the game, but it is a component that would really make the game complete. I would like to see a career mode that would give some context to the KSP and why Kerbal's are so happy to be in space.