Well, I got the system last night and tried the following games: PD0, Kameo, PGR3 and Geometry Wars: Retro Evolved.
Some quick initial impressions:
Xbox 360: Love the console. It looks really sleek and sturdy. Turning a console on with the controller rocks! I found myself many times, sort of moving my hand under the controller to 'get the cable' out of the way merely out of custom becuase the wireless controller was just as responsive as a wired one and I was just starting to get used to the notion of no wires with a controller.
The dashboard of the console is just amazing. Feature packed, really easy to navigate, and very nice looking. It took me all of 1 minute to go to my PC, set up Windows Media Connect, and set my music folder to be shared with the Xbox 360. Then on my Xbox 360, I connected to my PC and was streaming music out of it right away. I was impressed with how fast, easy and smooth that process was.
PD0: I got a really bad first impression with PD0. I thought the graphics, while sharp, left much to be desired. It really doesn't help that you start with a damn escorting mission. DEAR DEVELOPERS: ESCORTING MISSIONS SUCK! Anyway, I was also disappointed with the first level lacking any real control tutorials, other than a few things. Basically, I had to go back to the game manual to find out how to do some things. I initially stopped playing it in the middle of the escorting mission, because I HATE THEM, but later returned back to finish it. Turns out the next mission is much better looking.
Basically the controls are the typical for console FPS, but lack any sort of auto-aiming, like for instance the one we've grown used to in Halo.
Kameo: I found Kameo to be really great looking. Beautiful effects and particles everywhere and a very lush world. Gameplay seemed quite fun, as I was starting to get the hang of making combos and switching characters to increase the combo multipliers. Not much else to add here.
PGR3: This was the game I put in my Xbox 360 after PD0 (first game I tried,) visually disappointed me. I needed reassurance of some sort and PGR3 definitely delivered. It's buttery smooth and gorgeous. Unlike the previous versions, where you could tell the reflections weren't too smooth nor realistic, they look incredible in PGR3. Gameplay is as one would come to expect from the previous versions, and the cockpit view is insane. The glass reflections and lighting makes the game looks insanely real.
Geometry Wars: Retro Evolves is a CRAZY game. I love it. Those damn pink blocks that split into crazy tiny ones when shot are EVIL AND HAVE A MIND OF THEIR OWN! Mini-Game of the Year without a doubt.
Anyway, needless to say, I was very pleased with my purchase.