Well, Electric-Mayhem seems pretty pleased with his 10" Viewsonic. Though given he says the software he put on it is rather buggy I don't know...
Personally it's not that I'm bent on getting a 7" tablet - I see advantages to both sizes, so given that the Nook color is a decently priced option that's on sale right now that's why I'm considering a 7" tablet.
Sorry guys, I haven't been online much today and forgot to look to see how much response there was here. Didn't realize all the questions.
Build quality wise, I'm very impressed with the Gtablet. The front is a nice glass, scratch resistant screen, and the back feels like a nice solid metal one, probably aluminum but I can't tell for sure. Its powdercoated or anodized black though, and stays clean fairly well. The switches and such have nice feel to them, and the plugs are nice and tight. Absolutely no complaints from a build quality standpoint. Maybe not the most innovative design, but its very usable.
Usability wise, its a tiny bit heavy, but not so much that I can't hold it with one hand and use the other to navigate. It is missing a few features that would be nice, such as the home, back and menu buttons (all capacitive) being backlit. No vibration, so no haptic stuff. It does have an optional Dock, which lets you plug HDMI, additional USB, and a Network port in. It already has a slot in the side that has space for a Micro SD card, and a full size USB port, along with the mini-USB port to connect it to computer. Bluetooth and Wifi both work fine, though the range on the Wifi doesn't seem to be as good as a laptop.
Its hard to say on performance. The software that comes with it out of the box is ATROCIOUS, so if you can't deal with installing a ROM, don't buy this tablet. Viewsonic did release an OTA update that made it slightly better, but it still sucked. Very limited market access, still slow and cumbersome, and just not what it should be.
That said, there are two very stable ROMS for this tablet, both of which are based off the Tap n' Touch that the Tablet came with. One is called Vegan, and the Other TnT Lite. They both cut the fat away, and then add functionality to it so its much much more usable. The Vegan guy is in beta testing of a Gingerbread based ROM now, and I've heard he is on the CyanogenMod team for the Gtablet too now.
CyanogenMod was stable, but had a few critical bugs that rendered it useless for me until they figure them out. Most notably, you couldn't access the internal SD card, either via ES File Manager or similar, or via USB. Thats a problem for a number of reasons, but most notably it restricts being able to flash other roms since you can't transfer the zip files onto the root of the SD card. I actually had to completely wipe the whole tablet and then figure out how to get NVFlash to work to get it back to stock and start all over. Not a fun process the first time, since its REALLY hard to find the USB flash recovery drivers on the Nvidia site (you essentially have to download the ones for the development kits). I'm keeping an eye on CM, but until its got some of the bugs ironed out I'm staying away.
I got that all figured out, and am running the Vegan-Tab stock tweak ROM now. Its quite stable, but still not perfect. The machine and OS run fine, but its clear that a lot of stuff isn't made for a Tablet yet. Its more an issue with other Apps then it is with the on board software. I expect that to change in the next year or so, so no real regrets. Getting full Android Market takes a few steps, but its not hard and once I figured it out I got all the apps that I was really wanting and needing for this thing to do what I want.
The reason I jumped on this so fast is I am headed to Moab in a couple weeks, and want to use it for offroad GPS navigation and route finding. Oruxmaps allows you to download a number of different styles of map, which you can then apply GPS waypoint "tracks" to to know where the trails go. It sucks that the Gtablet doesn't have onboard GPS, but I think it could actually work a bit better having a external one since its more efficient battery wise, and they tend to have better features. I have my eye on one that has some nice features but is reasonably priced.
I'll keep everyone informed of how things go with it. So far, I'm loving it and have no regrets. This is especially true since its only going to get better from here on out with it. I don't see technology overtaking this tablet for quite a while, since its fairly cutting edge with the Tegra 2's.