One of the major things that I disliked was that in order to get the good ending (which left me feeling completely empty & wishing that I had just taken my initial path), you can't really kill people.... this would not be an issue if you had a nonlethal melee weapon. As it stands, the only way not to kill people is by choking them out from behind, using your SEVERELY limited sleep darts, or just avoiding them like the game's version of the plague.
Speaking of that plague... what exactly is it that it does? At first I thought it just made you die. Then I started encountering people who had the plague & they were all violent zombie-like creature so I just assumed that having it also made you insane. THEN about 80% through the game I met a whole group of plagued individuals that were nice, (relatively) friendly & didn't try to hurt me in the slightest. So my guess is that everybody else I encountered was just an asshole & therefore I don't feel sorry that they have the plague.... fucking rat bastards want to attack their savior, then they deserve to die a slow & agonizing death.
Something worth noting is the length of the game... if you go in with all your proverbial guns blazing & just ignore all of the collectible powerups & side missions, then the game could likely be beaten in around 3 or 4 hours. It took me around 15-16 hours (so a whole weeks worth of gaming) to do (at least I think) everything that can be done & following a mostly stealth related path. So keep that in mind when playing the game should you choose to.
Last but not least.... do not play this expecting some award winning story... there is a story, sure.... but I sure as hell couldn't tell you much about it (evidenced partially by the fact that I honestly *as stated above* don't have a clue what it is that the plague REALLY does).
Still, I highly recommend that you at least try it out, especially if you can get it at a decent price (or rent it at the library, like me).