I played about half way through and its solid. It's not a game I will want to go back and play but enjoyable enough to play through once.
Really good if you just want a filler until Watch Dogs comes out. Probably about 10-12 hours at a leisure pace. 20ish hours for collectible and uber runs. 8 for a quick run.
That's one of the reasons I picked it up, besides really wanting to play it. I also didn't have to hesitate since I essentially got it for $23+tax after you figure the 20% off GCU, $20 BBY RZC and $5 eGC. Plus I'm sure I'll be ahead after I trade it in next week (unless Target gets it in their system before close tomorrow).
As for the game, I'm thinking I'm just about 1/3 through it, and I'm really enjoying it. The gun fights/enemies really remind me of F.E.A.R.