I broke down and bought it. So far I've played for an hour or two.
I am very impressed with the quality of this game. And considering the quality, I'm even more impressed that they decided to sell it for only $19.99. It's amazing how these days, big-name software companies often release a buggy mess of a game, and yet a small indie developer can release something nearly flawless. I've yet to encounter any noticeable bugs. Even in the menus, before actually getting into a heist, it gives the impression of a Valve-quality title.
Yes, I'm comparing this to a Valve game. And not just because it's "very similar to L4D" (which is a pretty big misconception from gamers who haven't actually tried it), but rather, because it feels like all of the right design decisions were made.
The graphics, while nothing groundbreaking, are very pretty and clean. It looks good while running like butter at the same time. Think Portal 2-level of visuals. The audio sounds equally as great. The soundtrack does an awesome job of carrying the intensity of the game, while the radio chatter and bantering between your teammates really complete the effect.
Yelling at civilians, pushing them to the ground, and screaming "GET THE FUCK DOWN" is more satisfying than it should ever be. The gunplay, while not spectacular, is still decent. It's no Killing Floor or Red Orchestra, but more of a standard CoD type of feel. Like L4D, the pistols feel like pea-shooters. This makes sense though considering the fact that you're firing at very heavily-armored law enforcement units not far into the heist.
This game is challenging. Even on normal difficulty, if you mindlessly run 'n' gun into a group of cops, you'll get busted pretty fast. It's no Rainbow 6 either; Payday is still very much a shooter at it's core, but there's also a lot of strategy to consider.
Unlike L4D where you're slaughtering hordes of zombies, the enemies in this game are much more intelligent. Seeing the AI move from cover to cover, dive through windows, grapple through skylights, and snipe from rooftops is legitimately intimidating. Also unlike L4D it's fairly less linear.
Situations and objectives are different from game to game, which adds to the replay-ability. Even little things like shooting out the security cameras will have an actual effect on how difficult and/or successful your heist will be. In one game, after walking into the bank, one of my partners accidentally revealed himself way too early, which resulted in the alarms setting off. Consequently we had a harder time tracking down the bank manager so we could kill him and steal his keycard.
I know some people are unsure about the replay-ability of this game. After playing it today, I can confidently say there are at least dozens of hours worth of entertainment here. Although I've only been playing the game for one day, I've just been playing the same map (The First World Bank) over and over, multiple times, which definitely says something about the replay-ability. I haven't even touched the other heists yet. I'm excited to see what the other campaigns have in store.
Amazing value for this game.