Looks cool but gameplay is boring and unrewarding, skip this

堆怪，单调，第一个boss虫后打不过。真浪费我生命的2个小时

Pretty fun. The graphics and music are good enough. The gameplay is pretty simple. You kill enemies, collect loot and powerups, spend your money in various shops for stronger abilities, fight the area boss, repeat a few times. Both campaigns are pretty long. The game makes it really obvious that you should be playing this with friends, but if you've played any 2D shooter before, then you won't have a problem playing solo. Not even on hard.
You should probably buy it when it's on sale, it's more than worth a couple euros.