Yes, it is true that A. muscarina contains other compounds, but not in high amounts and muscimol is the primary psychoactive ingredient. Ibotenic acid is found in significant quantities in the mushroom, but it is not psychoactive. In fact, it's converted upon ingestion or through the drying process into muscimol!
I've heard plenty of bad experiences with the mushroom. This, combined with it's variable potency makes me hesitant to mess around with it myself.
So, I'm really interested in trying this compound in its isolated, pure form where I can be sure of purity and dosage. Hopefully one of you out there has tried it and can clue me in so I know what to expect!