I haven't seen Ghostbusters in a VERY long time, and as such my experience with the game was not filtered by much nostaliga. Because of this, I may have a different opinion of the game than many others.
The short version: Buy it if you're a huge Ghosbusters fan, rent it otherwise unless you find it for a good price.
The long version: The game is essentially a movie tie-in for a third Ghostbusters film that never happened. The story is original and written by Dan Aykroyd and Harold Ramis. It's good, for the most part, but falls into some cliches later on. Also, there seems to be a little too much of doing things that are a homage from the previous films. Don't get me wrong, the films were good, but this makes the game a bit predictable at times. Like, you KNOW you're going to have to fight the Stay Puft Marshmallow Man. There are a couple unexpected things near the end, however.
The voice acting is excellent. All the original cast is there save for Rick Moranis and Sigourney Weaver. Even the Mayor and Peck are voiced by the original actors, which greatly surprised me. The one weak point is Alyssa Milano, who plays a new character that is fairly devoid of personality. I'm not sure if this is more the fault of the writing or her performance, but I'll blame her because she's not Harold Ramis.
The gameplay is very similar to other third-person action games, most of all Dead Space, which is not at all a bad thing. You get cash for bustin' ghosts, which you can use to upgrade your different weapons. The weapons are nothing too unique. They essentially play like a lazer with a magnum-like secondary fire, flamethrower with a grappling hook, freeze ray with a shotgun, and machine gun that has a tracking beacon much like one of the guns from the Resistance series. They all LOOk unique, but they operate much like weapons used in other games, except that instead of reloading (you have infinite ammo for every weapon on singleplayer) you need to stop and vent your weapon when it becomes overheated. Trapping ghosts involves weakening them with your weapons, throwing a trap down, then wrangling them into the trap using either the thumbstick or motion controls (if you choose) on the PS3 and probably the Wii.
There's also a bit of an investigation element. You can find collectible items worth money in the game by using your goggles and PKE meter. You also need to use this to progress through parts of the game, and it never ceased to be fun for me. This mechanic is like an extremely simplified version of the CSI-thing in Condemned 2.
I have two major complaints with the game that almost caused me to give up on it entirely. The first is that several of the bosses are either uninteresting, cheap, or altogether not very fun. The second problem, which ties in VERY closely to my first, is that the teammate AI is TERRIBLE at times. I have spent more time during boss fights reviving my teammates than I did damaging the actual bosses, and I was only playing on the medium difficulty setting. Some of the enemies can incapacitate you or your teammates in one or two hits, and running around reviving teammates make the game feel more like an escort mission during some battles (or, in a sense, a bit like a tower defense game). Imaging playing Army of Two or Gears of War, and you lose your health and need a teammate to revive you. Now, imagine that said teammate is mostly worthless, and you have Ghostbusters. Thankfully the moments when you have more than one Ghostbuster with you seem fewer than when you either are alone or only have one person with you. Reviving one teammate is far more tolerable, save for one moment in a graveyard which had me cursing at Ray Stanz repeatedly because he could neither defend himself nor revive me without dying.
The multiplayer is, very surprisingly, my favorite part of the game. I have yet to try every mode, but the ones I've tried were entertaining, though not especially creative. You choose one of four main weapons (though you have the ability to pick up temporary weapons) and as you gain XP (cash) during multiplayer you gain upgrades to that weapon. Your choice of player models is limited to the Ghostbusters, and you can't create a character, so that was a slight annoyance of mine. Another small thing that I noticed and loved was a sort of title given to each player at the end of matches, much like the ones given to players at the end of sets in the Rock Band series. It's a bit useless, but it's fun and keeps things interesting.
On the PS3 it was good, but I felt it wasn't quite worth $60. $40 at best. The PC version of the game DOES in fact cost $40 (I believe) but I would recommend against buying it because it's lacking multiplayer of any kind. I'd wait until that version costs $20 or until they release a multiplayer mode.
Speaking of multiplayer, why, oh why was this game made without a co-op campaign mode (online or otherwise)? Nearly all of my problems with the game would have been solved if they either spent more time on the teammate AI or just given me the option of playing with PEOPLE. Nearly any human player would be smart enough to revive their teammates when THREE of them are unconscious at the same time. But I digress...
In summary, if you're a fan of the Ghostbusters franchise, you probably already own this or are planning on getting it, and rightly so, because it is extremely faithful to the series (perhaps to a fault). If you aren't, wait until it's cheap, or simply rent it sometime. Or ignore it entirely, because you're not missing a whole lot that hasn't been done in other games.
ARBITRARY NUMERIC SCORE = 5/12, unless you're really into the films, in which case add one point for the amount that you...love...Ghostbusters. Geez, I don't know. I can't measure love.
As an aside, I got a free movie ticket for buying it, so that was kind of nice. It expires after July.