Alot of fun and very well made. The weapons fire looks great as does the shield.
The biggest tanks were too easily defeated or should always be accompanied with a group of smaller tanks like in the very last level. I had all the best weapons bought before level 10 and all the upgrades around level 7 or 8 so I think they were too cheap.
Also, I never went over the weight limit as I didn't need to buy some of the cheaper heavier weapons as I had the upgrades
I really did enjoy this and it is currently my favourite flash game but making it harder by just tweaking the enemies' stats would make it perfect. 10/10 as it really does deserve it despite being easy it was still alot of fun shooting up the enemy and is replayable.