I think it's interesting how Volume 1 and Volume 2 have such different tones. Volume 1 is a bloodbath and has the trademarked Tarentino messing around with time and stuff, but Volume 2 is almost straight narrative with relatively few casualties, though those few arguably have much greater impact.
And yeah, the buried alive sequence and the eye-plucking thing are both pretty grim, and oddly enough both tie back to the Pei Mei flashback. That flashback seemed to go on a bit, and I was wondering what the point of it all was, but sure enough, it led to not one but two payoffs. Tarentino again; you never know what's gonna come back and be important later on.