Good, not great
I know you have stated you havent gone as far with this game as you wanted, but ill still give what you could do to make it better
The game felt really slow. Mainly because of the way enemys were spaced out, the mines and the fact it kept stopping and starting. It stopped way too much in the earlier stages, it got annoying.
The game had decent graphics, and the shooting/driving mechanics worked well. And they game had alot of lasting value due to being able to purchase upgrades and so on, although it could of done with more depth just to make it better. (Buy completly new tanks or something)
Overall, a good game but didnt match my expectations from the alpha :(