In my never ending quest for the 'perfect' tablet, I sold the HP Slate 2(Perfect Size, screen just too dim). And am now testing out a Skytex Skytab.
First off, the width and height are pretty close to the iPad(it's the same screen as an iPad 2 I think, or at least very similar), but thicker. So, in that sense, it's really a bit too big.
Here's the video showing mounting and location on a Cessna 172: http://youtu.be/WPVjSCH5mg4
The actual device is fairly nice, capacitive touch, 2GB RAM, quick processor. And now that I've cracked it open it has a 128GB SSD instead of the 320GB HD it came with. The screen is nice but it consumes a ton of power at full brightness, I'd put it at about 3.5 hours doing flying apps at full brightness.
The downsides, one, it's large as mentioned above; two, the power connector is stupidly fragile. My first flight I mounted it with the power connector down and cabled to an external battery(XP18000) and broke the jack at some point by hitting my leg with the cable. Luckily I had already figured out how to open it with the SSD install so it was just resoldering the jack and reinforcing it with some super glue to the board it was on. In addition, I've swapped the power plug with a right angle one and countersunk the case to reduce the lever arm for the plug some more. And, when flying with an external battery I'll put the battery plug on top, and use the USB on the bottom for the GPS.
So, for now it's a good tablet, and if you like the larger size and want windows it's probably nearly perfect(except the stupid power jack).
My next two that I'm going to be evaluating is the Sol Computer 7" Tablet if it ever actually exists: http://www.solcomputer.com/ because the Pixel Qi screen should make the battery life good and improve readability in the cockpit. The other thing I'm looking at is the various 8" non-branded Windows tablets available, with a 1024x768 screen I think the size should work much better, and also at a very nice price point, the 7" Windows tablets all seem to go up significantly in price.
Until next time, on my search for the perfect(not iPad) tablet for my flying.