Lots of good things to say
There are a lot of good things to say about this game. I'll touch on a few here.
I played through this game twice, with some time between both runs. The first time I used a nonlethal approach and the second time I killed all who got in my way. Both approaches are equally valid! The only time where the game lets you down is in a few boss battles, for which stealth and nonlethal aren't options.
Being nonlethal - either through avoidance or knocking people out - was very rewarding, but it requires patience and planning. Unonscious people can be revived by others when they spot them. This is immediate, no matter whether they were tranquilized or punched in the face. And those takedown animations show some massive punches!
Lethal is much faster, as downed opponents stay dead. It's also fun to play with the variety of lethal weapons. Some do start weak, like the shotgun, but can become very deadly once upgraded. Unfortunately the AI shows its limitations most clearly with this approach. Someone just shot at you? New corpse on the floor? There was an alarm? All is forgotten after a minute. And it is also a very good idea to walk towards that door with a pile of bodies in front of it, especially after hearing all those shotgun blasts.
You can upgrade your body throughout the game. Some augmentations are quite handy, others are quite useless. The good news is that you don't really need many upgrades at all to succeed, they're mostly a convenience. In both playthroughs I unded up with unspent upgrade points.
You can also look in every trash can, drawer, desk, whatever, and read all messages on every terminal. There's often credits, ammo, and bits of background info to be found. The good news if that you don't have to go dumpster-diving. In my first game I checked everything, but the second time I didn't bother with distractions.
There are a few social encounters where you have to talk to a key person until they give in. Some of these challenges can fail, which is fine because there are alternative ways to get what you want.
A word of warning. The first time you get to the office after the incident, there is an urgent matter to attent to. This is the only point in the game where stuff goes bad if you don't respond in a timely fashion. It won't stop you from playing the game, but lives are at stake.