...and being an old game hasn't made it any better.
This game features all the fatal flaws of a failed shooter. Horrible AI that while being hopelessly retarded is also godly accurate with any gun at any distance. Stealth mechanics that just don't work and force you to resort to save/reload trial and error to complete missions, which while frustrating wouldn't be all that terrible if you were not limited to a set number of saves per mission.
Maybe if the game was interesting otherwise, be it through the plot or level design or game play mechanics, it might be redeemed despite the above flaws - but it's not. The plot is a confusing mess, the levels while large are ugly and boring and the missions themselves start to feel like a repetitive chore before you're even on your second mission.
Don't get me wrong, this isn't really a bad game - it's just not a good one. It's completely forgettable and for all the things it does right, there are plenty of games that do it better. This was true when IGI2 was released, and it's even more true today. Open world and freedom? Play Operation Flashpoint. Tactical fights? Play Ghost Recon. Stealth? Splinter Cell.