I can't really decide to recommend or dislike. Wish there was a middle option.
So yeah. You can go and take apart guns, put them together, and watch how they fire. Pretty cool stuff actually. You start of with an AK-47, then unlock the M1911 (I think, haven't played in a while), then the MP5, and then you get a branching path that you can choose from. Each gun costs XP to buy, and when you complete stages like taking apart the gun, putting the gun together, firing the gun, using the gun at a shooting range, speed-disassembling/assembling the gun, etc. you get XP.
However, XP isn't HARD to get, it's just...ANNOYING.
The problem with this is that you get WAY to little XP to unlock anything before you become bored. I don't think I made it anywhere past 4 guns (AK47, M1911, MP5, Beretta). To get required XP, you will need to constantly go back and play all of these games OVER and OVER again. It gets boring, trust me.
I GUESS it would be good to buy the DLC for this, but honestly, just trust me, using it for something like this might not be the best idea.
Is it a bad game? Well, sort of. They tried to make it a game, but I feel like just making it an interactive thing would have been much better and I would have given it a higher score. It's really interesting how you can do this stuff, and the guns are great, but since it's so annoying to get the XP needed to unlock the guns, you probably won't get to a lot of them. If they just lowered the XP required or dropped the "free to play", put a cheap price tag on it, and then unlocked all of the guns, that would be better. It IS great for gun enthusiasts, though, and I guess it wouldn't hurt to try it because it is free.