Its the same as the first game with a new character, new locations, more mods/weapons and a few beneficial tweaks. If your interested watch reviews of the first one. The GameSpot review was not an accurate reflection of this game, it almost seem like the reviewer didn't play much of the game. I personally liked it more than the first one because its more open, the new character is ridiculously fun to play as and the sewers and prison in the first one were very tedious.
Oh yea it's only $40 on steam, for me it was a no brainer, wouldn't be the first time I enjoyed a game GS hated or hated a game they loved.