I have two (one for me, one for the wife).
It's a decent tablet, very hacker friendly. The screen is pretty low quality. It's fine when viewed directly but have extremely limited viewing angles.
I love mine though...running CM7.03 (CM7.1-RC0 is out), and I can do near/most everything I do on my Droid. Great for web browsing, Kindle/Nook books, Email, playing games, watching Netflix....
Tegra 2 CPU, 512 Megs Ram, 16gb internal storage, sd-card slot, USB slot, docking station port (I have a dock for one...charges and HDMI out). It's decently fast, 2400 quadrant scores on average.
Pros:
Great for hacking. Froyo ROMs, Gingerbread ROMs and Honeycomb ROMs available.
Fast, plenty of storage, can take USB keyboards or Mem sticks. Development community is decently active. PRICE - $299 typically to $249 on sale. (started at $399 when I bought mine)
Cons:
Screen...will be the biggest complaint. You HAVE to hack/mod it to make is useful (stock ROM is total crap). A tad heavy considering the newer lighter 10.1" tablets hitting. Only WiFi, no 3G, no compass, stuck with Froyo drivers so Gingerbread and Honeycomb are hacked and use software decoding for video, etc....
Xda-developers has an entire section to it.
Viewsonic G Tablet - xda-developers