This is the type of game I grab for under $5 during a Steam sale and then play here and there to kill time.
It's got a lot of negative reviews on Steam and they're well deserved, but not...
The good:
It's a classic side scroller. The graphics are really crisp and sharp. It can be beaten without tricks. The enemies are varied, as are the weapons. Stages are varied, although more so in the second half of the game. It'd be a game you could let your kid play. The longer you play, the more you'll get used to the controls and enjoy playing.
The bad:
It's got some bugs. It suffers from a severe lack of polish. Some levels you'll have to restart simply because you used keys on doors that are pointless (trial and error). The controls take a bit to get used to due to a weird jump that has you glide down.
Overall, it's not one I'd recommend, but it's not as bad as some of the reviews indicate. I mean, if you got it for a dollar or two...it's worth it.