Bought one for my son for Christmas, seemed a pretty decent spec with metal gear diffs and ballraces. He's destroyed a front shock tower already but at £1.50 each the parts are pretty cheap. Also had to fit a variable resistor in the tx to slow it down (he's only 7!)
I wouldn't think they'd stand up to much racing abuse, but as a cheap rtr for 1/18th scale they're a good deal.