It's decent. Nothing extraordinary, but very detailed model. Recoil is solid, fire rate is good. The attachments are only a grip, flashlight, suppressor, and extended magazine. The grip and flashlight kinda ruin the aesthetics of the gun, IMO, so I left them off. The unsuppressed sound is excellent, though.
More information I found on the subreddit detail how there's a hidden timer of 20 minutes. The crimescene only spawns after those 20 minutes, and even then it's on only one of 10 possible spots, spread all over the map.
All in all, it was a bitch to hunt for the parts, and the gun is barely a decent reward. If you have the time to hunt for it, I'd say go for it. Otherwise, you're not missing out much.