Simply put a lot of fun! I love RTS mechanics and the ones you implemented here kick ass. I'd love to see the game play balanced out to be more difficult in the future, maybe some caps on how many of a certain unit you can birth? The potential of this game rocks though, and the execution of what you got done within the time limits is also very impressive.
The progression system is really cleverly thought out, I love the idea of having you produce your own units to fight enemies, and being able to upgrade to stronger units as you recover hostages and complete missions. Well done!