I've been out on Blackbeard's twice and loved both trips. But I loved the trip at Thanksgiving much better. That was Thanksgiving of 2002 and the vis was fantastic. I went back in May of 2007 and the vis was not what I expected. It seemed that all the coral had a haze over it (spawning?). I went in May of 2007 single and found a buddy immediately, she happened to be my roommate.
They do a shark dive and you can feel the anxiety before that dive. Just add a few pounds to your weight so you can stay on the bottom and it's fantastic. The sharks don't come until they hear the panga (with the bait ball) hit the water. That won't happen until everybody is in place and comfortable.
As an additional note, I've been diving single for 5 years (diving a lot longer than that) Yes, it's a little disconcerting when the operator calls and says HI - we have 4 couples, 7 men and YOU. He did offer to give me all my money back but I wouldn't give up the Galapagos islands. As it turned out, I eventually did get a female roomate, not one of the original 16 passengers.
If you want to PM me, I'll give more info.