Not bad... not bad at all...
First of all, you need to be able to buy troops in bulk. That's the big thing. Next, I'd say you'd need to be able to see more of the troops you've got in back up. Those little arrow things just are not cutting it. Think, Inventory box, or something like that. the skill points things I like. But it need an ending. I dunno, something like "Woo-hoo, you've enslaved the world!"
Without an ending, it feels a bit empty. Maybe have a villian of some sort?