The first game is a childhood classic, but I've never played this one before so I decided to give it a playthrough. Before I played the campaign, I played a little multiplayer before it's servers were closed down, and truthfully had a horrible time playing against people who knew every corner, crack, blind spot, and exploit to basically spawn kill me. I was able to learn some of the ropes, but it just wasn't fun enough to continue.
The campaign on the other hand was awesome. The stakes are way higher than the first game, with a mission to find, locate, and destroy a terrorist weapon that uses scalar technology to cause mass destruction. Playing on the hardest mode, I had a blast, with me only taking a couple days to fully finish the campaign, as it really isn't that long. The level designs were everything you'd want from a game like this, the story was serviceable, and the ending was a blast. Definitely recommend for 1st person shooter fans.