It's not a QTE. It's a new stealth system they've implemented where you have a choice when you melee attack from stealth of either killing or knocking them unconscious. Effectively it adds a short cinematic to your melee stealth attacks. It's really not much different from attacking someone with the dragons tooth or the riot prod, you just have 2 seperate buttons instead of picking your weapon before hand. The skill is in the sneaking part anyway.

Not sure about the killing of the 4 guys though. I'm taking a wait and see approach as to how they'll implement that one. It looked like it may have even been a time-slowing/reactions aug rather than outright killing 4 guys.

From what I've read they're not really QTEs but part of the new stealth system. When you melee attack someone from stealth it shows a short sequence of you taking them down. It also gives you the choice of outright killing them or knocking them unconscious, only the other gaurds can now wake them up if they find them.

Also, remember this is a trailer made for exciting the viewer. Everything I've read suggests the convos are as long and involving as in the original and without the stupidness of IW (some characters really didn't work in that game). I honestly don't see how they can screw this up as much as IW screwed up.

I've got high hopes for this but the fact Warren Spector and Harvey Smith the creative directors from the first two games don't have any thing to do with this one i ain't too sure how it could turn out.

i really hope it lives up to my expectation which by th way are average, but excited.

The graphics don't look as good as I expected but i guess the same thing happened with the first deus ex.

The gmeplay on the other side looks extremly rich with a lot of variety 

Could be very good, could be disappointing. I hope its not watered down as much as some other games have been this gen, the RPG elements are paramount to Deus Ex and are by what made the first one so unique and deep and damn enjoyable.

The thing with the sword though was that I'd kill one and the other wone would get a shot or so at me before I chopped him up. Add that to the already present regenerating health system and you end up with almost no reprecussions for just killing smaller groups of guys, cause hey your health will be full anyhow!

The part where he killed 4 people it lookes like he spun and shot bullets all over the place, killing the 4 people at once. I'd love to know how in a prequel they found a way to kill more effectively than in the future.

I heard the AI is quite good on this one (from PC Gamer) and that the stealth system is designed so that it doesn't make the AI look stupid like in the first, so hopefully that'll compensate for the double stealth kill ability. Forgot about the regen health... which isn't an ideal situation, but medpacks wasn't the best bit about the game, although I'll admit I liked the different body part healing.

Okay.  That would be better - a little visual reward for pulling of a good stealth move.  I would really, really hate to see QTEs in Deus Ex.  I don't like 'em in God of War never mind this title.

Worst case scenario:

Cover-shooter, QTEs, regenerating health, stealth and roleplaying nerfed, long-ass cutscenes.