Black Flag is the first game in the series I haven't bought on release day.
I was not looking forward to it, simply because it seemed more like a cash grab to please the people who liked AC3's sea combat. I wasn't a huge fan, myself, so it didn't appeal to me. I was also concerned about the setting. Islands and small town in the 1400's Caribbean don't exactly scream 'EPIC HEIGHT' to me. I just didn't think the AC game play was very conducive to the setting.
Having said that, I've been renting it from RedBox for the past few weekends. I'm actually enjoying it far more than I expected I would. So much so, that I've been looking at buying it. But I'm reaching the point where I think $60 is just too expensive. If this had launched at $39.99, I probably would have bought it day one. Now, I'll wait until it goes on sale for $34.99, maybe on BF I'll pick it up.