One of the most fun open world games around and makes a great alternative to the rather serious GTA IV series!
I haven't played SR1, but in terms of the story, you're reovering in a prison hospital after getting blown up on a yacht at the end of SR1. With the 3rd street saints disbanded, you're assisted by a guy called Carlos and with him, you escape from the prison Island to the newly developed and rather large City that is Stilwater. From there its now a tale of where you take the lead of the saints along with returning character Johnny Gat and other supporting characters to take over the city from 3 other gangs and put the saints back on the map!
Whilst the story feels like GTA;SA, you almost can make it your own, when first starting the main game you're asked to create your own character/avatar who will be the protaganist in the main game. you can absolutely customise your character in any way you like such as male or female, fat or thin, race and personality and later you can purchase clothes and accessories - so you can really adopt your own 'Swagga' to your character.
Although I could question the story continuity as you could only customise a male character in SR1, but now can have a female character if you wish.
Moving on with customisation, you can later customise your gang, purchase and customise your cribs and vehicles which can bring a fund element to the game.
Buying items will build up your respect multipler which helps you to gain 'respect points'. These are needed if you want to progress the story and complete missions. The way to earn these points is by doing various things in the game between missions in the form of activities (crowd control, drug trafficking, Fuzz - like the vigilante missions in GTA, and one of my favourites Insurance Fraud) and more), diversions (car surfing, ambulance missions, base jumping) and certain actions (narrowly missing other drivers in cars, drifting, jumps, throwing people and other crazy behaviour!). Doing these crazy things gives you more respect and occasionally gain additional rewards like special weapons and cars. Love it or hate it, its that mad but so much much fun!
Whilst many would argue its just a GTA clone, to me its not as it has its own style and makes a great alternative to GTA. Graphically its not the most advanced in the world but lighting and shadow effects are suberbly done, cars whilst not licensed, do look fairly similar to their real life counterparts and the character models are not bad at all. Although there are glitches every now and then but it certainly doesn't ruin the core gameplay.
The audio is really good and the voice acting is nicely done and has recognisable voices in the game - like Daniel Dae Kim (24), Michael Dorn (Star Trek TNG), Eliza Dushku (Buffy the Vampire Slayer, WET) and Keith David (The Thing, Mass Effect). There's a fairly decent soundtrack in there too, like GTA, there are in game radio stations for different tastes and the general sound effects are pretty good.
The game presents a good challange but not overly taxing, you're up against 3 gangs in the game - the Ronin (yakuza style), the Brotherhood (hispanic/rock style) and the sons of samedi (voodo, jamacian style) love them or hate them, they are vicious and very trigger happy in their own right but the overall AI has a good balance in game.
I can't comment on the multiplayer as I don't have access to go online at the moment, but even in offline mode, there's so much to do and so much fun to be had in Stilwater, it certainly has become my guilty pleasure.
If you like the seriousness and realism of GTA, you may want to stay away from this title. But if you love over the top, total nonsense gameplay with a view to create you're own unique character, then this is an absolute must buy!
With Saints Row; The Third coming up later this year, definitely pick this one up to keep you occupied until its released!