UPDATE:
(and apologies for not following up questions)
the tablets I got are MID brand, no serial #'s. my 4yo dropped his, screen shattered.
my 10yo did 'something' to hers, the screen got a single hairline crack, I suspect it was from pressing the screen too hard.
the 12yo still has his, working fine, great for his task app and games like angry birds.
so my final opinion on cheap tablets is, you get what you pay for. functionally, they are fine, these even have a google play icon (where alot of them don't)
I think the cost cutting is in screen durability and battery life.
they CANNOT compete w/ nexus or ipad, but they are much cheaper, so buyer beware.
fortunately, I did buy warranties from squaretrade, and they just paid me the purchase price. they are awesome.