So in the first game, you get recruited into the Saints, and take control of Stilwater by taking out the other three rival gangs. You then get 'sploded in a boat. In the second game, you wake up after being in a coma, and find the city has been taken by three new gangs, and the Saints have been crushed. You take the city, by taking out the new gangs. Easy.
Well, in The Third, you start with control over the city, and then try to rob a bank. You fail, and make another gang, The Syndicate, mad. They take you up, try to negotiate, and you being the awesome stubborn guy you are, you get yourself thrown out of a plane. They take Stilwater, and now you need to take a new city called Steelport.
So, the new gang is actually one gang, with three divisions (Naturally..). They consist of The Morning Star, The Luchadores and The Deckers. Apparently instead of the gangs each having a separate storyline, their stories are interconnected. This means that the direction you choose to go with one section of The Syndicate, will influence what happens with the other two sections. There will also be multiple endings. Should be awesome!
Saints Row 2 introduced multi-player and co-op through Xbox Live or system link. The Third will not have multi-player matchmaking, but will still have co-op. This means without the multi-player, there will be more focus on the co-op side, which in my opinion was the best part of Saints Row 2!
The gameplay looks a lot smoother judging by the E3 gameplay footage. There also seems to be a lot more melee-style moves available to you at the beginning of the game. SR2 was notorious for the huge amount of things you could do as small side missions, which would give you bonuses. Well, SR3 apparently has a lot more of that.
There is also a new way to, i guess, "Level up" in SR3. Respect points before were only really used to gain access to missions, but now, they can allow access to a perk-store, to help you finish the game your way.
New weapons have been added, including a Laser Designated Air-Strike, a and a Remote Controlled bug, which can be placed on vehicles. Also included is a err.. adult play thing..
The ability to customize weapons has also been added, which includes adding scopes to your arsenal or a larger clip. I assume you'd be able to add guns to cars as well..
Vehicles have been redefined, and are now easier to drive. I think they were easier before, but hey, whatever works!
Remember in San Andreas, when you could eat a lot, and you would get fat. Well, now you can do that on Saints Row! This will probably mean you won't get as much customization at the start of the game, but moreso by exploring and finding customization places.
At the end of certain missions, the player will be able to decide the finale. For example, killing prostitutes, or sending them back to the Saints HQ to boost gang morale.
Health regeneration has been added, so you don't need to always have a constant supply of food, although they will probably keep it for emergency situations.
Graphics, physics and destruction of vehicles are also being improved.
While all these features are being added, or tweaked, I can't help but think that SR3 may be setting itself up for fail. I mean, Laser Designating? That seems a little too far, even for a Saints Row game. Nonetheless, i can't wait for it to be released, hopefully it's as good as THQ is boasting! And now, we wait..