Bare, empty, and plain. The Doom 3 version you posted had more detail and variation then this corridor maze.

Did you run cubemaps? Because it looks like the models are lit incorectly.

Sort of clean for a powerplant, imo - The walls could use a different tex, and the supports look too angular - Good for HL1, but you can curve things now without worrying about r's.

This is for doom three, not hl2.

It looks like it is all one hallway with enemys. Is there a story and a reason for the player to be killing all these people?

The hall-ways are too empty.