A waiting-for-drills- and bag throwing simulator, which is highly addictive. Just look at the time I've invested in the game...whew.

New content on regular basis, which usually costs a few $$$, but if you're OK with that, then this game will keep you busy for a long time.
It has a big community base, always a lot of people online, which is a must if you intend of playing with other players and not just offline by yourself.

If you end up having all the paid DLCs and a lot of microtransaction skins/safes like me, then here's a tip for you: don't add their values up together and find out how much you've spent on the game, just see each new DLC as "Only $4,99 for some new great content? Sure, why not?"