TL;DR -- this system is as good if not better than all of the hype you've heard about it. Simply phenomenal.
I got X1 at Midnight and was home by 12:10, which also included dropping off a guy who had gotten one and didn't have a car.
The update took about 3 minutes to download. Upon finishing, the system rebooted for about 2 minutes, and then setup began.
Everything went well, but I wasn't able to really use the Kinect because my wife was asleep in the next room, and the Kinect setup requires you to purposefully turn up the volume a lot higher than normal. I eventually got to use it with my wife this morning about 3 hours ago.
I will say that the only hiccup of the night occurred when trying to install COD:Ghosts. It seemed like it took absolutely forever (probably like 20 minutes) to both DL the update and copy the disc to the HD. Not the end of the world, but it seemed a lot slower than usual. BF4 went a lot quicker.
I've got to say, MS has far outdone themselves. The UI is clean, yet elegant. The Kinect voice commands have worked every time I've used them this morning, assuming I actually used the right command and attempted to speak up/enunciate properly.
The system, after 9 straight hours of gaming, wasn't hot at all, and the fan is really quiet.
The only negatives I've encountered is that after I finally shut down the system and then rebooted it, it didn't seem to identify me or my wife very well. It has a built in protocol for when this happens, and seems to indicate that over time it gets better, as it sees you in different lighting, but that did happen this morning.
The only other negative is that both my COD and BF skills appear to have totally atrophied over the last 5 months of no gaming. I have been getting an absolute train run on me all night.
Sorry for the rambling nature of this review, but I didn't sleep all night, and my brain really is struggling.
If anyone has any questions, I'll be happy to answer.