Is the creature sacrifice enough of a drawback to make it a reasonable ability?
Not even close. I agree that maintaining tokens isn't that hard. Or, just having regular creatures. Which isn't hard for black to have.
Is his high cost enough to push him into 'safe' territory?
Not really, though it puts him into "safer" territory. 4 mana vs 8 mana is a big difference, but EDH is built on big splashy plays so CMC alone is not often enough.
What are the general reactions when he drops?
"I need to kill this right now" & "I need to focus on that player that just tutored up 3 unknown cards that will probably kill us". Obviously the latter isn't always true, but the mind set is that I need to assume it is true so we don't just die.
How much value does he typically get? Does he win/end games?
I have only seen him a couple of times. One time he did end the game but that was more due to the insane mana generated by Black Market to fuel the X spell they tutored for. And the other time I don't feel the player was really playing him "right" since I never saw them get anything worthwhile off of him. They might have been setting up a combo that just never materialized I guess.
Is he exciting?
For the player casting him, absolutely. A big demon that can tutor stuff at the cost of your life seems exciting. But, for the other players, I am not so sure.
Answered in the embedded quote above.
Overall, I don't necessarily think he is banworthy, but the few times I did see him he was just part of the 99 and did a lot of work. I wouldn't be sad to see him go since, but I don't think he is there yet.
Answered in the embedded quote above.
Overall, I don't necessarily think he is banworthy, but the few times I did see him he was just part of the 99 and did a lot of work. I wouldn't be sad to see him go since, but I don't think he is there yet.