I'd agree that it's the vocals, live, that have disappointed me most when seeing Mastodon on stage. It's a shame as they sound so killer on record but I think they are (or were) very hit and miss live. I hope to see them soon though as it's been YEARS since I've seen them perform.
On a side note, does anyone else have that thing when a new album is due to be released and everything seems to click? Like, the singles are great, the promotion is great, in studio clips hit the spot and you dig the album art etc. It happens sometimes (as it did with this new album) and you almost make your mind up, before hearing the album, that you are going to love it. Of course sometimes the new album may be a real disappointment but sometimes you are convinced this new album is going to be all killer, and you're correct!! I almost knew that this album was going to exceed my expectations (and it has) but do you think that is because you subconsciously cut it some slack and love things about it that you may have been more critical with on another album or that it coincidently is just as good as you hoped.
It's a strange phenomena and I'm sure it doesn't only happen to me, thoughts?