First and foremost, there's 2 things I feel I need to talk about. One, is the micro transactions. EA, the publisher, seems to have decided that micro transactions are the future - at least for their games. So, for Dead Space 3 (DS3), they added micro transactions in the form of upgrade supplies. Basically, at any time you could spend your real life dollars on in-game materials in order to build more health packs, ammo, or weapons. I'll talk about this a little more later on, but while I was very worried about how micro transactions would affect the crafting components of this game, in the end my fears were not realized.
I enjoyed upgrading my guns once I got a few different things to try out and resources became a little less scarce. It was fun to change things up as the game went on, since you can only equip two guns (instead of 3 like previous games), but each gun can have up to guns essentially stuck together. I tried a lot of combinations, like dual plasma cutters, or plasma cutter with flamethrower, or rifle with grenade launcher. There's also small addons, like a scope, an ammo box that auto-reloads the gun, and even addons to give each shot a bit of fire, electric, or stasis.
Parts of the game have you fighting actual humans, and I must say those parts I found myself think "ok, let's just get through it and onto the next interesting bit". I mean, Isaac (the protagonist) might be a pretty hardened guy after his last two adventures, but I don't see him as the type of guy that can murder entire troops of soldiers - up until now he's almost only killed necromorphs. Not to mention, the "bad guy" was extremely cheesy and over the top.
The game was quite long, it must have taken me around 20 hours to complete. This is quite a bit different from the last games, and not necessarily for the best. I just found myself not really caring too much for what was happening. The few NPC characters were forgetful. Even in the first game when you don't see the NPCs I felt more attachment to them. In the first one, you're finding out all kinds of interesting stuff about what happened. You see video and read text logs of people who slowly went insane by the Markers. You piece together the puzzles of what happened, and figure out exactly what happened on the Ishimura - and it was terribly interesting. In DS3, you're entire goal is to end the Markers and so there's very little investment as the game has now become a hero-adventure.
Back to the co-op, besides the disappointment at finding doors locked to my single player experience, at least they made the co-op partner stay out of my game. Basically, he continually winds up on the other side of a door or broken passage or whatever and you end up taking different routes to the objective, so that you don't have a stupid NPC tagging along with you like in that Resident Evil game nobody likes.
My final thoughts are this: the game was mediocre. It was lacking in story and development, and is only a shadow of it's former brilliance (for those who appreciated DS1). While the first game was confusing, you felt like there was enough threads to piece it all together, but in DS3 the head scratching was more about what the writers were thinking. Bad plot devices move the story along, and in the end the game is only really saved by it's interesting crafting feature and still pretty intense action scenes, even if they are horrible obvious.
Worth playing, but only because you've already played the other two... if you've never touched a Dead Space game, please just try the first and maybe leave it at that.