The Grabber, which is Nerve and ID's piss-poor attempt at ripping off HL2's Grav gun, is really useful for only two things: throwing Imp fireballs back at the Imps, and tossing flammable barrels at enemies; and the latter happened so infrequently that it might as well not be. As for the first, sometimes I'd rather just pull out my regular guns and just put down the Imps the good ole-fashioned way: with a hail of lead or plasma.
The double-barreled shotgun rocks though. Each BOOM really feels like a BOOM, and if you're close enough, you can put down most enemies with a single blast.
A little spoiler section about that "artifact"The artifact here basically has three (or four, I forgot) levels, which you advance every time you beat a boss. The first two or three make you slow down time around you, so you can run rings around your enemies and pack em with lead up close. The latter levels also makes your weapons insta-kill, it seems. Activate artifact, pull out shotgun, run up to Hell Knight's face and put it down with a single shot.
You have to find human souls (basically normal human bodies) to recharge the artifact.
The artifact is much more offense-oriented than the Soul Cube, which may or may not fit your tastes better. End spoiler.
What else is there, oh yes: The end boss of the expansion is MUCH harder than the Cyberdemon of the original. You can probably guess that it's Betruger, and he's pretty hard to put down.
As for the ending? Blows balls even harder than the original Doom 3's ending, if you can conceive of that.
