Not too shabby! Definitely didn't have the best first impression due to the bland asset-flip looking graphics and menus and the lack of juicy special effects: like c'mon, why when you kill the boss does he just stand there and then pop outta existence? There should be a big explosion and he should fly away and such to give you the satisfaction of completing a level! You already do it for the regular enemies when they die, so why not for the boss too!
Anyway, looking past that, the game was pretty fun and addictive to build up your army and deal with whatever formations the enemy is sending out each level. In particular I liked how the units have different movespeeds to them, which forces you to think of the logistics in depth: you might want to deploy a unit to reinforce your fighters, but you need to factor in whether they will get to the frontline fast enough, and so on. Very interesting stuff!
One big thing that really bothered me is when I upgraded a unit and suddenly the cost of deploying the unit was increased as well: I had no idea it would work like that and it really screwed me together since I had lost a strategically low-cost unit and now had to grind previous levels to try and get enough cash to buy a new unit that could fulfill that now lost role. Felt like this was really uninuitive: would love for the units to be redesigned so upgrades don't influence deploy cost, or to have the ability to undo upgrades.