Picked up the volume today and just finished reading it. Lovely.
Higher quality image of the new volume cover.
http://imgur.com/qvPKMGQ
I must say, the colors on the physical volume look subdued and darker (or duller) compared to that ^ high quality image.
In terms of differences with the volumes that came before, the image on the inside of the sleeve is lovely, as always and comes in a new border/frame with a Beherit on top. Everything is now bordered - the cover, the inner sleeve small drawing and the new image of Puck on the back of the cover. The empty spaces of the cover have this granite/marble-like effect vs plain white on older volumes.
Difference in the spine (I need to make room on the shelf and couldn't picture all past volumes)

The back of the volume with the granite/marble-like effect

The volume also came with a promo-sleeve like the last 3 volumes. I don't know what it says! It looks like there are signed copies of the volume cover (?) and Beherits with dates for a promotional thing (maybe those are YA release dates and there's something Berserk related in those YA releases?)

Here's the sad part from my visit to Kinokuniya - I went through the Japanese volume section to find Volume 1 with the alternate cover and I walked through the entire section, keeping in mind I was looking for a long stack of volumes on the shelf but I couldn't find any Berserk. I'd walked through 8/10 aisles twice now. Afraid the store might close soon, sought help and went to the info-desk to ask if they had Berserk volumes in Japanese. The helper got up and exclaimed "Yeah, we have them but you won't find them easily. They're on the shelf facing the window and we only have a few" ... when we got to the shelf, they only had Volumes 33, 36, 37 - that's it. Volume 38 was being sold up front, with other newly released manga. I was honestly extremely surprised and blurted out a "That's it?". The helper said "Yeah, not many people buying Berserk. There's a long wait for each volume. We don't have other volumes at the store".