I believe it's an expansion pack. It adds a few new guns, a few new suprises and a few new enemies. It picks up in storyline after the ending of the first FEAR. Anyone who's played it will know what I mean... BOOM!!!
Anyway... Play the DEMO and you'll get a taste of it. Graphics aren't any better from the DEMO.
Think of the DOOM 3 Expansion Pack... Same idea...