Needs a lot of work.
You've got a good BASE here, it still needs a lot of work. A lot of the bugs need to be squashed and the AI could use a slight boost. (Enough to not just idly sit around and do nothing while I blast them to oblivion.)
Also in dire need of some explanations of what Unit's do. It wasn't until level 10 or so that I felt the need to upgrade my units. (For a change to my massive ant army.)
With some polish and work this game could very well turn out to be one of the best Flash RTS games to be played.
Overall, for what you have so far. It was a decent play.
P.S. The music was pretty boring, should try to mix it up a few notes.