I don't imbibe (for that matter, pretty much anything stronger than caffeine), so I can't offer any information about the experience of its affects on rationality.

From the literature, it has a relatively high ratio of activity threshold to lethal dose (even assuming the lowest supported toxic doses), but that usually doesn't include behavior toxicity. Supervision is strongly recommended. There's some evidence that psychoactive drugs (even weakly psychoactive drugs like marijuana) can aggravate preexisting conditions or even trigger latent conditions like depression, schizophrenia, and schizoid personality disorder.