First reaction: Woah! That is MASSIVE!
It's certainly large, much larger than anything you'd carry around as a portable, but you can easily slip it into a backpack.
The hardware feels sturdy and the build quality is excellent. The rubberized grips feel great to hold and help keep the SHIELD stationary when you put it on a flat surface. The screen is pristine; it's a 720p but the display is sharp, the colours are vivid, and the viewing angle is pretty wide. The clamshell formfactor helps keep it compact and also feels sturdy, it doesn't feel like the hinge is loose or anything.
The gamepad fits snugly into my hands and it's essentially like the X360 controller with the analogues in the middle and the d-pad off to the left. The d-pad, buttons, and triggers got quality treatment and shoulder buttons in particular feel much better than the X360. I would seriously consider using this gamepad instead of any other.
For the software, it's running on stock Android 4.3, latest available for the SHIELD, and it comes with a couple of complimentary games: Sonic 4 EP2 and Exile, both immediately gamepad-friendly of course. There's also some Nvidia-specific stuff like the TegraZone app and the Console Mode app (which automatically launches when you connect the SHIELD via HDMI). The TegraZone app gives you immediate access to games that are optimized for the SHIELD and also to the streaming feature, which sadly only works with GTX Desktop hardware, not yet available for Notebook hardware, so my GeForce 780M can't stream to it. There seems to be an alternative which some people claim to be superior to Nvidia's streaming:
Splashtop.
The virtual gamepad mapper helps as a workaround for games that don't support gamepads by allowing you to customize which buttons or gestures map to physical buttons. It's pretty awesome and Nvidia have done a thorough job in making it functional and very easy to use. I've made my own mappings for
Swordigo and the game is so much better with a physical gamepad!
Honestly, with regards to the software structure, this is exactly what Sony should have done with the Vita: an Android device that can run major games and still retain traditional functionality, giving you the ability to install your favourite Android apps. Wanna sell Vitas? Make them useful. Sony already have an Android distro with the Xperia, so why not capitalize and mod it for the Vita?
Anyway, coming back to the SHIELD, it's definitely a hardcore item that's difficult to recommend to the average gamer, let alone general public. I've yet to test the Console Mode but if it works as I imagine it could very well be one of the SHIELD's strong suites as a streaming solution.
I'm going to delve deeper into my experience with the SHIELD and see how I feel about it in a couple of weeks.