Cliched but fun.
The plot doesn't bear scrutiny, but how many game plots do? The graphics, well they're quite Half-Life 2 (obviously running on the same engine), but with more of an "old school" feel, which permeates the whole game. A great deal of effort has clearly gone into making the main female characters look good, the sexiest polygons I've seen... ...yes, I know that's a bit tragic; your sidekick is clearly an Alyx Vance wannabe, in keeping with the whole game's seemingly self imposed Half-Life 2 wannabe-ness. Voice acting is good, if a little hammy at times.
The gameplay? I dunno why, but I just kept coming back to this game for one more go, it's just great fun! The comical level of gore is hugely satisfying, chain gunners expolde leaving legs with a bit of spinal column, with a head lying 30-odd feet away, headshots are rewarded by pieces of flying brain! The guns all feel great, err, all three of them.
There's been a lot of gripes about the game's length, but considering that it's meant to be an episodic piece of content, and that it's available through Steam at $14 (+tax), the length was fine by me, especially as it's full of shooting fun rather than waiting a good chunk of the game before you get a weapon (unlike a certain more high profile release...), first time through will take about 5 hours, but it can be done in about 3. Other reviews have said that the difficulty level adjusting to your level is flawed, but to me, this is a work of genius. Flawed maybe, but your access to your stats gives the game tenfold relpay value!
All in all, this is FPS by the book, but done really well.