Mine locked up on me about 5 times yesterday. I wasn't even doing anything strenuous with it - on the first occasion I was trying to copy a ~45mb file from my home server over Wi-Fi. The other times were just trying to load a web page.
The whole thing locked up on all occasions. I hit the reset button on the back, and it then would sit at "Turning on WiFi" for ages - all I wanted to do was use it for the F1 driver tracker yesterday, and it took until well after the end of the race for the WiFi to enable.
The final time it froze yesterday, it got into a boot loop - and there was an awful squeeling sound coming from it.
It's also practically unreadable when there's any daylight behind you - my sofa is in front of the window, so unless it's dark outside, I can't use it on the sofa.
There's thin black vertical lines every cm or so down the screen, very obvious when you're trying to find an angle where you can read it during the day.
The touch is also too sensitive, when trying to scroll down a list in Settings, it'll select something in the list rather than scrolling, and it keeps trying to pinch-zoom in Firefox (I had to get an add-on to disable double-tap-to-zoom, which made it slightly better)
Usual story applies here I think - as a basic device, it'll do the job, but as an enthusiast (as you are if you're on this forum), you're likely to be frustrated with it.