Pros: Great story, excellent sense of humour, lasts long. Cons: Collecting intel is pointless (gains you nothing)
For me, it's the variety of settings, all very well designed, that really make this game stand out. You'll go to Morocco, a tropical rainforest, a few office blocks, outer space and snow-capped mountains and that's about half of the different locations, which does a lot to keep you interested. The game will last you well over 15 hours as a result of all these different mission and it very much feels like Monolith went above and beyond the call of duty because they so wanted to tell this story right.
Also, I liked the fact that it's not all run and gun - stealth plays it's part. Some missions are exclusively intel gathering, and if you kill anyone it's game over. This doesn't happen all that often and as a result, it works as a break in the intensity.
Story is well told, although I felt the Elite Guard girls weren't really worth having and should have had significantly more backstory, although maybe it's a 60s reference I'm not getting. Also, the voice actor for the main character is a little wrong but I don't know how to explain it, she just doesn't sound right occasionally, but it's not off-putting. The main thing about Cate Archer is that she's a positive female lead in an industry that usually would just put her in a bikini and have her run around using her sexuality to win over her enemies, a highly lazy way to write an action game involving women.
My only real complaint is with the intel gathering/rating system - it's pointless. Whether you gather all the intel in a level or not, or whether you get a good rating or not, it doesn't change anything in the game. Surely it should allow you to carry another gun, or give you special items? Anything to make the hunt more worthwhile, especially as most of the things you pick up are just joke memos that aren't really worth the effort. You don't even get an overall rating at the end, it's that badly implemented.
However, that's the only flaw in what is otherwise probably one of the top 10 PC games of all time. Music and sound is outstanding and the LithTech graphics engine is surprisingly competant for over 6 years old at this point. Buy this immediately.