I have to admit that a sequel to the original seemed like a stupid move but technically this is a sequel like Final Fantasy VII and VIII are. In other words not a sequel at all. Sure it happens after the event of the first game but the only things it has in common are the location and that Andrew Ryan is dead. Regardless here's my review of Bioshock 2, the unneeded sequel that was still a lot of fun.
Bioshock 2 is based several years after the events of the first game. You play as a alpha prototype Big Daddy know as Delta and you are in search of your original little sister who is now being held captive by her mother so she can turn her into the ultimate person through ADAM. The game plays exactly the same as the previous one so it'll be easy to get back into the swing of thing and it does have a tutorial to help as well. Like in the first game you get plasmids and gene tonics to enhance your character and this time you get even more to use on you at one time and there are some new ones as well. Along with more plasmids there are more weapons... well 2 new weapons but the others are the same except instead of a Tommy gun you get a Gatling gun and you can dual wield them with plasmids. Researching has also changed to a video camera that monitors the way you fight the enemy to do the research and hacking has been changed to a quick time event which actually makes it easier. Also now when you get a little sister you can gather ADAM with them and the last games moral choice system is back so if you want to see both endings you got to play twice. Look Bioshock 2 is pretty much just like the first game but with some extras. They also added multiplayer which is just mediocre so unless you want to play death matches in Rapture it's not going to make you leave your main online game anytime soon.
Is Bioshock 2 any good... yes. It has a good story that will keep you pushing through to the end and killing splicers never gets boring. I give it a 4/5 because the single player game is great but don't both with the multiplayer unless you desperately want the achievements. I still think that if you played the first, don't feel obligated to play this one as well.