Just got my Gentouch today. After a lot of updating and modifications, I've just about got it where I want it.
jgray's assessment of the hardware is pretty much spot on. The resistive touch screen can be finicky, but it's much better after loading the calibration update and doing a calibration (use the stylus for this). The microSD slot is painful. You have to be very careful about insertion (the metal connectors on the card face the screen, and don't accidentally slip it into the body of the case!), and removing the card at least for me requires a pair of tweezers.
I was able to update the device on Win7 64-bit after installing the Android SDK. Windows couldn't find drivers when the device was running, but when you follow the flash instructions (hold the back button, press the reset button, keep holding the back button until Windows connects and the device remains on a black screen) it was able to connect in "fastboot" mode. I don't know if it worked because I had the SDK installed or not, but if you can't get it to connect in fastboot mode for flashing try installing the SDK (search for it, it's easy to find with lots of guides on slatedroid's wiki, etc).
I've rooted my device, changed the launcher (default launcher doesn't change orientation when you rotate), got the market working, added "Button Shortcuts" to setup a long-press of search as "rotate screen", installed "Auto Memory Manager", etc. I haven't tried changing the MAC address yet, but as of right now I only have the one device so no network collisions to worry about. Once the community or Augen have fixed the MAC address I'll take that update as well.
Hopefully 64-bit drivers will be available soon. In the meantime, I've forced the device to use the SDK drivers for ADB access. This means I don't get access to the SD card over USB for now except through ADB (Android SDK debug tool), so loading books from Calibre requires unmounting the SD card, pulling it out with tweezers (see above), putting it in the SD card adapter, connecting it to a PC, and publishing from Calibre to the /ebooks/import folder so Aldiko can see the books. That's a lot of steps but at least it works for now.
Overall, It's pretty much what I'd expect from a $150 chinese device. It has its problems and it's certainly no iPad, but it's not terrible and has a lot of promise. If Augen keeps up with support and/or the hacking community continues to poke at it, this will be a pretty sweet little tablet in the very near future. Too bad nothing can be done about the terrible resistive touch screen.