It's about 5-10 times less toxic than ethanol, this is based on LD50 in rats.
However, it's about six times more intoxicating based on studies in rats. Now How that transfers to humans? I don't know.
The literature does state that the body metabolizes 1-butanol more slowly than ethanol. So be careful how much you drink if you're going to drink it because apparently it's much more depressing for the central nervous system than just ethanol.
I am in no way promoting that you drink it