Ok, let me see how can I put this:
Remember how in the forum I said that Payday looked bad and that I had no interest in this game and that is was derivative and boring and I hated it and I never, ever would ever play it in a million years?
Well…
Payday is excellent.
Yesteday Tokey, Johnny and me played two or three levels and we had a load of fun. I thought I would make a small review here so that you can see how wrong I was.

The first thing you need to know is that  this game is very, very similar to L4D. That is very high praise coming from me and my 200 hours of zombie shooting.

What these people have done is taken the basic mechanic of L4D (4 player FPS coop teamwork) and many of the core tools that L4D used to enhance it and THOUGHTFULLY changed the setting and tweaked the rules. And it works!

Just like in L4D, you carry resources like ammo bags that you need to share, you see the silhouettes of other team players when they are in other rooms, you can help up fallen comrades… it feels L4D.
However, it is not a complete L4D clone. The setting is very different, you are a criminal going through various assaults, sometimes on a bank, sometimes on a drug dealers den. It really tries to make you feel like a robber in the heist of the film HEAT, one of my most hated films of all time. I hate Michael Mann, even if I agree that HEAT is his best work. And the game succeeds in doing it. The weapons feel powerful, the levels are well designed, they are simple to understand and yet very dynamic, they are well illuminated, the sound is clear yet strong… this game has flavour.
The designers were very clever, because when they started designing all these missions, they realised that they were going to be extremely linear and guided. The game tells you all the time what to do: Go here and plant explosives, then go there and capture that guy, now go two floors down, kill one guy and steal his key. L4D does not really tell you what to do, it is usually very self explanatory and yes, it is also linear because the level design is linear, but it does not feel as linear as Payday does. In L4D, less is more, you do not backtrack, you simply push buttons to open a door or raise a bridge or something. Payday is more twisty but still exactly as linear. So what is the problem with linearity? That it can become a corridor shooter like COD or BF single player modes and that when you replay it it will get boring really fast. But Payday has got to be linear and guided, the bank heist theme imposes it. Are there ways to still make it fun in the L4D style of fun? Well, the designers have some very good answers for that question.

The first answer is that Payday is about following a path, yes. With emphasis on teamwork, yes. But it ALSO is about ammo management. It is designed so that even in the easy levels you will run out of bullets and need to share with your buddies. The most ammo that a group can carry will run out very fast if badly managed. The team needs to coordinate if they want to place the ammo bags in the right moments and spots so that everyone refills and the team can go on fighting. It means that you are constantly aware of how much ammo you have left and it introduces an extra task that feels very exciting.
The second answer is that although the game does not have the AI director of L4D, it has other tricks, specially the level design. One level is all about moving fast through a city. We did not manage the first two times because although we shot well, took cover and managed the ammo, we were too slow and ran out of ammo against the infinite respawns of the police. So the game is designed to keep you on your toes or you will be punished. The third element I noticed is that the levels are much more interactive than a typical L4D level, you can do things to affect the amount of police that tries to stop you, for example destroying security cameras in a bank. Or capturing and then freeing civilians in exchange of a captured member of your team (Although there is respawn, it is extremely slow, in the order of the 5 minutes).
Compared to L4D, each level is more complicated and much longer than a single scene of a campaign but it is still shorter than a full campaign and it cannot be divided in morsels, you have to play the whole thing through. That means that there is going to be a certain fatigue at the end, a certain feeling that you cannot keep this fight up for much longer because you are almost out of ammo, almost out of time and down on health. But it comes at the right moment and feels very good when you finish a level.

So as you see, the game has a lot going for it. I am really surprised at this game and I think they did many things right. On the bad side, the lobby is worst than L4D and I did not succeed joining a game in progress. Also, I do not know if the game is very long. We played 3 levels yesterday and they felt great, but I do not know how many there are. Still, as with L4D, game length is not easy to measure. L4D looks short but I clocked 200 hours on the first one. It is till too early to know if it is fun enough to be as replayable as L4D is.

A small note on the bots: they are like L4D bots, very good teammates but dumb enough that a team of 3 is much worse than a team of 4.

So to finish, I am going to say that this is an excellent surprise. It feels closer to L4D even than L4D2 and I for one intend to dive into it.