I've had some goes at it now. Twice with 2 players + 2 AI and about 3 or 4 goes at single player.
It's a flawed game for sure, and need's patching, what game doesn't when it comes out these days.
I wouldn't rate the AI as very good personally, there's often enemy standing next to you not shooting at you.
For all that though, it is challenging, intense, and fun. It wouldn't be worthy of a $40 or $50 purchase but at $20 it is priced about right. If they fix it up a bit, it will be an even better buy. I still haven't successfully finished the first heist after the roughly 5 attempts, which is good, being challenging.