I think one thing that makes this album distinctly different off the bat was that Brendan O'Brien was behind the mixing boards doing production duty. The two albums prior were produced by Matt Bayles. The band was so intent on trying to change things around and felt that they wanted a natural musical evolution from Remission, then to Leviathan and Blood Mountain, and now with Crack The Skye. I think one conscious reason behind this change is that there are other bands like Nachtmystium and Baroness (I highly recommend picking up the untitled Red album) that are also creeping into the sound that was first mined by Mastodon.
I actually welcome the new sound. I was curious to see if the group could write shorter songs and incorporate longer guitar solos into their bag of tricks. In that respect, the experiment proved successful. This is a band that has members that continue to challenge themselves musically. I also think that they have an obligation to the major label they signed to...who in turn wants to see a profit off this album. This is the fine line artists have to walk to please everyone in the process.
I'm totally psyched to see the album played in it's entirety tomorrow evening. For this leg of the tour, Intronaut and Kylesa will be doing support duty. I'm excited to see those bands as well--perhaps moreso for Intronaut though.