Well, just finished Old Man Logan. Umm. It's dark. It's got that twisted Mark Millar sensibility to that. I don't understand why he felt like adding in that incest angle to it, other then hey... it's something fucked up and gross and shocking. I guess we've come to expect as much from Millar, and he's just rising to the expectation.
But as a future dystopian tale, it really doesn't rank up there with TDKR or Kingdom Come. Millar doesn't try and weave anything profound or thematically rich into the story. There aren't even any internal narration boxes, from what I noticed. It's much more of a simple yarn, with some shock value. The emotional payoff, where you finally discover why Logan gave up his claws, is actually effective and completely surprising. It does satisfactorily explain why someone that violent would turn around and become a pacifist for 50 years.
I did enjoy it and would be interested in seeing a sequel series, if only to see what other twisted developments Millar would come up with for this Marvel Universe.