I bought a Zenithink C71 a few weeks ago. I've been using it a lot. Much more than I had expected to. I wanted it simply because it was cheap and wanted to play with it, and maybe install KDE Plasma Active on it (as this is the device they use for the Vivaldi tablets). I'm still using the rooted Ice Cream Sandwich it came with.
The tablet doesn't seem cheap to look at, but on closer inspection it doesn't hold up quite so well. The device feels light but slightly plasticy and bendy. The screen wobbles and blurs in certain areas if you apply pressure accidentally. This doesn't bother me too much though, I've learned to be gentle with it. There's a piece of dirt under the screen though, which is annoying.
The battery life is what you would expect - a few hours of use and a few days of standby. This didn't seem like much to me compared to a higher end tablet and thought it might be a problem. It's not, at all. It lasts a longer than my phone and spends most of it's time near the charger anyway. Not always plugged in as the supplied charger is pretty damn short.
Android 4.0 performs well. It's not lighting fast when you've got a few things on the go, but it's satisfactory. The screen can be a bit slow to come on and show you the unlock screen when you press the power button. Live wallpapers can be a bit juddery for a few seconds.
The cheap Chinese tablet has almost completely replaced the functionality of my desktop and my netbook when it comes to 'consuming content'. I use the Google Reader app, which works brilliantly. The swipe feature to get to the next post is really satisfying. There was a bug with this when I first used it, which caused minor frustration sometimes, but this was ironed out with an update, and the Reader app gets plenty of updates from Google. The app lays itself out differently depending on the tablet's orientation, but both layouts are useful.
The tablet wins because of its size and shape. It's like a book. Easy to carry around in a bag and not have to worry about breaking it. It comes with a slip-on carrier case. It's always near me for quick fixes.