I agree it would feel VERY dated now, but I played it not that long after its release, and it was one of the best game experiences I've had...listening to the logs was like the best part (aside from the midway twist), so well written, so much more interesting than the Bioshock ones, I felt a chill when I heard 'Oh Anatoly...we are not Korenchin...'
The twist was even more genius than Bioshock, and I thought Bioshock's one was pretty clever, both had the right amount of clues.
The atmosphere was so scary, hearing the mutants screaming, especially early on when you knew they could give you quite a beating...and as for jumpiness, I thought I'd cleared an area once, went to press some button, and when the hybrid's shotgun went off behind me on the rears, my mouse went flying across the room and I got hit repeatedly as I retrieved it
Its hacking mini game is pretty naff tho...