Just finished, and wow. Excellent throughout.
Combat gets a bit easy towards the end though, least on medium difficulty. Pricing structure gets thrown out of whack thanks to the U-Invent. The most powerful weapons and ammunition becomes much more plentiful than the crappy stuff.
As for replay value, don't really see much of it, except maybe to see the other ending. The game is necessarily linear in order to tell a tight story, and thanks to the swappable plasmids/tonics, you aren't confined to one play style on each run through.
Still, no SHODAN.

I don't see how Irrational is going to top themselves next go around.