Yeah, OP was probably referring to methanol or ethylene glycol rather than isopropanol.

Isopropanol basically causes most of the same symptoms as ethanol, albeit with less euphoria and a much worse and longer-lasting hang-over. There is no benefit to drinking ethanol, because unlike methanol, the most toxic component is the isopropyl itself rather than its metabolites, so you want to metabolize it as soon as possible rather than slow it down.

What it does, in large doses, is affect the osmolality of your blood. Your neurons can't adapt as quickly so if your blood's osmolality is high enough they'll lose intracellular water and shrink, which can lead to seizures, brain damage, and death. It can also erode the gastric lining, leading to vomiting blood, and inflame the pancreas, leading to pancreatitis. That said, this is extremely similar to what ethanol does and the lethal dose is essentially the same, 4 - 8 g/kg of isopropanol and 5 - 8 g/kg of ethanol. Other alcohols can screw up your blood's pH as well as having nastier metabolites (e.g. methanol has one that causes optic neuritis / blindness).