The single player for Ghostbusters is a lot easier than JC2, and it doesn't take nearly as long. The online on the other hand is a bit of a grind, and people have had trouble getting the trophies to unlock. They do eventually, but it can be a major pain. Have a look at the GB forum before you give it a shot.
Hey man, I was looking at your Three Stages of Hell Club. I finished Mercs 2 and am 61% done with Just Cause 2. Is Ghostbusters a grindfest like Just Cause 2? Cause I'm going to be around 90 hours minimum to get that freaking 75% trophy for JC2!