And, you know all deadliness aside, most people don't have good luck with them. Yeah, they're pretty, but what good does that do you if you don't see it once until it dies after three weeks? I believe that, more than the danger, is the most compelling reason not to keep these guys.
I'm not going to say no one has had luck with this species (there's a really good video on one of the threads here of someone's blue ring) but given the volume of them that are imported its extremely rare.
If you're serious about octos, set up a 75 gallon specimen tank and get a bimac.
Dan