If you found Doom 3's hallways fun (mike me) this one continues the fun.
Well Doom 3:ROE takes place 2 years after Doom 3 when UAC lands on mars after reciveing a distress call . As you investigate the ruins you find an artifact, when touching it unleashes hell...again. With this artifact you can get bullet time, beserk mode and eventually god mode. The new artifact opens up new gameplay elements, along with a couple new guns. These guns are the old double barreled shotgun, and the grabber (very similiar to gravity gun). This expansion starts out with large rooms, and ruins. But eventually winds down to the hallways.
So if you found Doom 3 a enjoyable game you will find this enjoyable as well.