I rarely have a reason to give a 4 or 5 star review, but this game does the job. The pace of the game for upgrading parts/guns is nice and swift so there isn’t much grinding, which makes the effort/reward ratio pretty good. No wait timers, only one form of currency, quick loading screens.
The guns in the beginning of the game are very sensitive to aim, which can get a little frustrating at times, but once you get to the MG-42, it gets a lot easier, almost too easy, actually, you don’t really even need to upgrade it.
And, as others have mentioned, it does get a bit repetitive once you get far enough into the game. Different ‘enemies’, bonuses for completing a level with 100% health, longer levels and bigger bosses at the end of levels would go a long way. Power-ups during play would be fun too, even if temporary.
One nitpick...I originally downloaded the game onto my iPad, and when I downloaded it to my iPhone, my game data progress didn’t transfer over, so I’m back at the beginning. Never had that happen before so I hope they can fix it, not that getting back to where I was would take long.