So I just got back from the "event" and got hands on with everything thankfully so I will try my best to answer the questions already asked while writing this: I have tried my best to properly edit this but I know it won't be 100% correct. There are no pictures to show as they would not let us take any, I am still not sure why.
So I was pretty impressed with the controller as it was pretty comfortable but it was not much different from the 360 controller: the sticks felt better as the little grips are gone and instead are around the edge stick, they did not feel much different to the 360 while in use which is fine for me.
I was impressed with the bumpers and the triggers, I tend to only use one finger for both and I found that moving between them much easier and felt more natural, mainly because the triggers and bumpers are wider then the 360 ones and there is no space in-between them so you can slide you're finger across.
The biggest problem is still the D-pad, I did not find it enjoyable for the 10 games of Killer Instinct I played, I found that the two controllers used on the demo station had different feeling D-pads, one felt much better but its hard to explain why: I had no problems dashing and fireball/shoryuken motions on both but it felt a lot "smoother" on the controller on P1 side: I got some of guys I was playing with to check it out and they said the same, I tried the other D-pads in use on the other stations (which had different games) and I did not have this problem with any of the other ones.
I found the rest of the controller to be much of the same, the buttons felt fine and thanks to the battery pack being in the controller I found a better resting place for my fingers as on the wireless 360 controller I tend to push my fingers against the side of the battery pack, which of course is no problem with the wired one I have. The only other thing I can think of is the cable, the one thing I don't like about the 360 cable (on wired one at least) is because the cable coming out of the controller is flexible it tends to pull to one side so I have to move it out the way of my fingers: in this one (and all of the cables at the back of the console) have the square style connector.
I tried to use the guide button and what happens is the game minimizes to a square about maybe 1/3 or 1/4 of the screen (while still playing) on these dev units the only thing you can see is a "Welcome to the Xbox One Demo SDK " I am guessing you would get other customization options but nothing was select able, I tried both buttons but in the middle of the controller: the one on the left did nothing ( and the other one paused the game. I asked about buying the controllers and stuff before launch and the Microsoft man said they would go out before launch and it would be up to the companies to decide if they sell early: the same thing happened with Pokémon last week with shops, one company sold early and everyone followed.
The consoles ran very silently and I put my hand on the vents and it was not warm at all, the Forza console crashed once: I never saw it happened but they said some sort of error message came up and it crashed. From what the Microsoft guy said it can take up to an hour to change from one game to another on the SDK, or to set it up (as they are moving from town to town every day until launch so all the demos and consoles get reset and have to be set up again)
I am going to write a little about each game, don't take much of this stuff as fact and what not, I only got about 20 minutes with each game, I only went back to KI after the first go:
Killer Instinct: I liked it a lot, I don't have any previous experience with the franchise but I am a big fighting game fan, SF4 is my game of choice which was great as I found it very easy to jump into, I only played Jago so I can't comment on the other characters (4 in this version) I liked the art style and the explosions from the fireballs (unblocked) look awesome, as well as the fur on Sabertooth looked nice. I never checked the move list until my last match but I was still able to bust out 40+ hit combos with ease before then using the simple this is a ryu clone tactic: some of it was mashing of course and it seems like after you do x amount of hits it just lets you keep hitting them for a while but in return it seems like unless you do a super move or special move the damage taken can be restored (similar to the first hit in a Focus Attack in SF4) I don't think there is much else I can say, if I pick up a Xbox One it will be my main game, apart from the D-pad issues (even without the broken one I would really like a fight pad from Madcatz!)
Dead Rising: I only played this for a little while as the demo had no missions what so ever, just the open world but what I can report is the frame rate in the demo was perfect the whole time, the demo was not the same as the conference one: it was an outside area and had a big shopping mall, I mowed dawn a ton of Zombies with some sort of construction vehicle with a scooper on the front and like a digger on the back which you could move from side to side like a brush just throwing everyone out of the way and before I ended my time with the demo I tried to get some vehicles and set them on fire, I never saw any dips there either but as for the load times I could not find any buildings that loaded when I went into them but when the DR3 demo ends it took a good 2 minuets to load out to the main menu then another 2 to load back into the world. I asked the Microsoft man about the Lawn Mowers but he did not have an answer (my guess if its not in the demo they don't know)
Ryse: So the demo was a co-op only demo that was based in an arena but it was mission based as you progress from one end to the other so for example kill these barbarians, set fire to this village or enter this fortified base and kill these generals all while trying to gain favour of the audience (basically not getting hit else they get bored or getting stylish kills on enemies to excite them) at the end of the demo you get a score and you can start again, that's it.
The combat was pretty generic, its a one button attack system with A being used as a Batman style teleporting/flying instant block (which I did not like as for some reason you can't use the shield any other way) you can also get people into a killing blow state simply by hitting them a few times (indicated by a skull on their head) and you can press B and kind of QT event in which you can choose how to kill them: if you are near you're co-op partner you can do a co-op finisher (the one I saw was the other guy holding him like a meat shield, I did a few stabs to the gut then it looks like he snaps his neck but the camera goes back to normal.) You also somehow summon lightening to push everyone back and stun them quickly? I honestly did not understand what happened/how is this possible, even after a few times of trying it.
After playing it I got the feeling this mode is the same as the multiplayer in God of War Ascension: another reason to keep the game in the drive but not especially worth while.
Finally is Forza, which was the most popular game was pretty enjoyable and everyone who I spoke to said they enjoyed the Impulse Triggers, the are pretty subtle and I enjoyed using them in corners: when accelerating on Laguna Seca track (the only track) I found the vibrations to be subtle and gradually increasing as I accelerating but as soon as I applied the brakes hard I could feel the Triggers going at full vibration, as well as the shock from the rest of the controller: I know in the promo videos they have talked about how it will make newer players better, I can't really agree and I am sure people will get tired of it after a while. Triggers aside I can't really comment on how well it played, it looked nice but I did not feel the AI was any different.
So all in all I was not swayed either way by the Xbox One, I was not blown away by any of the games, on either a game play or technical level and honestly could not point to a sole reason for buying the console or if it has any true or worthwhile improvements worth the investment: I currently have a PC very capable of playing the new games as well as a 360 but I did not walk away with a bad feeling out the system either.