The problem is that you played Resistance about sixteen months too late.
Back in 2006, Pre-gears and pre-CoD4, this was really good.
If you played it when it came out, I'm most assured that you would have a totally different view on the game. But in the scope of CoD4, resistance isn't that great.
You really can't [and shouldn't] call games "forgettable" after a year of release.
That'd be like me saying that Gears of War is forgettable, since CoD4, and Rainbow Six Vegas, and Halo 3 were better. When Gears came out, it was great, but after these games came out, playing gears feels downright archaic.