Pros: all the great things remain and there are more new ones
While in the first game, you have spent almost all of your time in the USG Ishimura, here for the most part the action will take place on a space station called Sprawl, build around the Titan - one of the Saturn's moons that by according to the story was "cracked". Apparently a necromorph outbreak takes place on the station and Isaac Clarke, once again, finds himself surrounded by the necromorphs and tries to fight his way through the station levels just to escape. The story is a bit more sophisticated this time and deals about the inner conflict between the unitologists and the government, and your personal involvement in the creation of the new marker, yet unknown even to you. The story is not really that important compared to action and you will find little of it anyway.
Gameplay - same as before, and that is enough said. You can be assured that you find all the same great horror elements from the first game and be delighted throughout it. At one particular part of the game you will revisit the USG Ishimura - this time the planet cracker vessel will have a totally different inside look, as if redecorated before a major renovation, and with that said everything inside will remind a construction hall for some concert hall rather than a planet station, familiar places without their patterned stains will sure add new depth and make you feel more comfortable, but then the major question will remain - does the ship still contain necromorphs after renovation?
Dead Space 2 does not add much over the prequel, but what is new makes up for a new experience. While you have played Dead Space, you know that RIG was the key object in the game - all the things you could do were related to it. Obviously Dead Space 2 brings a modified RIG.
The essential improvement includes the ability to impale necromorphs with any sharp object by using the telekinesis feat. Telekinesis was already a cool feature in the first game and you could bash objects at monsters with it, but not kill them, and this time it works as a real basic and most important weapon - you will be using this feat until you will grab a hold of a weapon that you carry with a hand.. This new feat is really great when playing on the hardest difficulty, as there are twice less ammo on hardest difficulty.
Another modified RIG thing is the way you move in vacuum - Dead Space 2 allows you to fully fly, and not just boost up from one platform to another, and that is, of course, an improvement.
New weapons will be available throughout the game, and obviously the majority of the old ones will be there too, but what is really new is the ability to upgrade weapons further than before - their microschemes will include new circuits and the ultimate new ability when fully upgraded. For example the new javelin weapon has a primary attack mode of firing bolts and a secondary mode of electrocuting monsters from those bolts, and when fully upgraded gets a new ability of exploding those bolts.
Now the final and perhaps the most disappointing part comes from the RIG itself - you will find many new forms of suits to ware, and of course, the upgrades done on one suit will carry to another, and every new suit will have it's special ability, so that is cool, but what is not cool are the promised extra new suits available on hardest difficulty, once the game will have been unlocked - the PC version simply "forgot" to include those new suits... Whatever, playing the second time on the hardest difficulty does not become that attempting once you know you won't get your promised toys..
Apart from the mentioned new stuff there is not much new in general - the controls will feel the same, and the graphics look the same. The game is not a demanding one and will run smooth on average gaming machines. There are some bugs present though, particularly the annoying is the disappearing objects bug, which causes the objects you carry with telekinesis to disappear, so i will give a warning - do not bother to gather the stakes when going from one room to another...