The Vizio tablet is a pretty great budget model for a kid or someone just getting started in the Android world. It's impossible to root, but the stock OS is decent enough that it's not a huge problem. That said, we don't use ours all that much since we have other, better toys.
The TF300 is my primary Android tablet, with the keyboard dock. I LOVE THIS THING. When my laptop was off getting repaired for a week, it's all I used for regular computing, and it was great. With the addition of the dock and a free RDP app, I can use a real computer through it and the experience is just seamless.
Three things on the TF300:
Get a screen protector. It's not gorilla glass, and it will scratch. I am SUPER bummed that I have two very small nicks in mine (I'm obsessive about keeping it looking brand-new), but I got a screen protector for it that hides the scratches. I ended up getting an antiglare GreatShield (three-pack for $10 shipped on eBay), and it's awesome. It's a better touch surface, doesn't get fingerprinty, and most importantly it doesn't interfere with the keyboard dock.
The keyboard dock requires a 15Vcharger, and the tablet will charge very slowly on a 5V 2A charger (e.g. what comes with iPads, the TouchPad, and pretty much every Android tablet out there). This in mind, DON'T get a cheap Chinese power adapter as a backup charger. The touchscreen is extremely sensitive to "dirty" power (e.g. a transformer that isn't high-quality with a very clean, steady voltage output) and flakes out if you're using a crappy power adapter. It's also theoretically possible that such an adapter could shorten the lifespan of the battery in the tablet and/or keyboard, so if you need a second one buy an OEM one on eBay or Amazon ($20 on Amazon, super saver shipping eligible).
If you get the TF300 and it's already running Jelly Bean, I wouldn't recommend updating it quite yet - the newest system update disables Moto Chopper. If you're running build number 10.6.1.15.3-20130416 or older, Moto Chopper is a one-click root that is persistent and won't void your warranty.
Hope that all helps someone!