I just finished this game. For the past few days, I've done nothing else but play it during my free time. I thought Splinter Cell rocked, but it is nothing compared to Deus Ex HR. Wow! It even has it's own version of zombies in the ending!

Downloading the bonus content now... didn't know it was a separate download from Steam. Then I'm going to replay this thing again on hardest (Give Me Deus Ex!) difficulty and see how far I go.

Just a few observations...
1. Combat rifle is crap, just a waste of space. Other guns can do more damage, ie heavy rifle or plasma rifle.
2. Sniper rifle is so-so. Can't take out targets with head armor with one shot.
3. Upgraded pistol is the bomb! Head shots on all but armored targets; if the target has head armor, the pistol can do two shots better/faster than the sniper rifle.
4. Grenade launcher useful for mobs.... or boss.
5. Tranq rifle may be useful for "timing" takedowns. Tranq one guy then pistol-head-shot the other and both go down roughly the same time so nobody raises the alarm.

On my second run through, I'll probably survive with just the pistol, the tranq rifle, and a sniper rifle for long-range head shots.

What a time sink!

On my replay, I'm using the pistol for my main weapon, giving it the good upgrades. Then the assault rifle. Keeping the silenced sniper rifle (dlc) for when I actually have the ammo for it. Otherwise, the Typhoon is the way to go for bosses and bit bots.

On my first playthrough I went completely non-lethal so that meant using the tranq rifle, takedowns, the taser gun and that EMP gun (forgot what it's called). I decided not to go the lethal route since that would have made the game very similar to first person shooters and I didn't want that.

Absolutely. The fully upgraded typhoon makes the boss fights so much easier.

I'd LOVE to play this more Splinter Cell-like and non-lethal, or at least all silent--the inventory limitations make the crossbow a waste of space, although it's a lot of fun to pin people to the walls. If they'd just give us decent ammo amounts, inventory space and fix the energy cell system to you can fully recharge, it would make the game a lot more fun IMO. At least as an option for subsequent playthroughs.

Yep, I just might go for that Pacifist achievement... though this run-through was more stealth than thou-shalt-not-kill.

I've not used the Typhoon much simply because of the build plan... I defeated the first boss with a combat rifle, the second with a heavy rifle and some well-placed mines, and the third with 4 shots from my best buddy the grenade launcher! The end stage scene was very easy to do with just those rotating turrets, so I'll definitely replay this with the hardest difficulty. Hell, I've had a tougher time making sure I went through all the cabinets and read all the emails...

Raw Kryptonite, if you refer to the combat rifle, I'd say it's not worth it. I upgraded mine with a silencer, that auto-homing upgrade, laser sights, etc... still crap. You want stopping power? Heavy rifle. You want quiet head-shot takedowns? Pistol. You need to reach across the map for a head-shot? Silenced sniper rifle, though in this case, it might be easier to sneak in closer and use the Pistol again.

Hopefully in my second run, I'll get more options with grenades and mine placements since I'm not lugging the sniper rifle and the combat rifle around.

There's very little the pistol can't handle well, even some long shots.

Yep, but found it easier to aim with the sniper scope than it was to put the laser dot (and hold it!) over the target's cranium.

My second (and so far last) play-through was completely non-lethal (except the Boss fights, which, BTW, I find contrived and anti-climatic). The only reason you'll need a firearm in the game: the aforementioned Boss fights.

You'll get most bonus points by playing non-lethal, and it is the most challenging way to play the game.

Its funny how different people in game react to your character, depending on how you play the game.

Interesting, didn't know that. Maybe I'll try that the next time I play this game through and go all aggressive.

Never used any lethal force (except for the bosses) because, as you said, the game is so much more fun and rewarding going all stealthy and taking opponents out unseen, silently and without killing them.