They're worth nothing regardless of condition... which is what makes them fantastic.
Anyway
Compared to a Corolla, the panels are thinner, the interior plastics are cheaper and nastier, the general build quality is terrible, and the frames are lighter and twist and split all over the place when you put any sort of serious power through them, which is why its always better not to, unless you're going to put a cage in and seam weld the whole car. Oh and the gearboxes are poo.
That being said, a stock 120 with an A12 engine will run rings around any rolla with a 3k.... with an opened up (carb and exhaust) A14 they are a legitimate road weapon.
My old one would leave V6 commodore drivers blinking repeatedly in disbelief as this shitty old dented up datto tore away from them at the lights, and held them off quite easily up to 100kph...
I miss my datto :D