tl;dr: A manga that feels like it's being pulled around randomly and has a lot of rough edges but comes together pretty well despite that. 

Something that makes this manga interesting is that it feels like the author changes his mind about what he wants to do quite often, which at times completely changes the course of the story. This is most notable in that it started on a path, seeming like it was going to become a pretty standard high school sports manga, before all of that completely fell apart suddenly. After that there's a time skip and it seemed like it was going to become a more extreme sports manga, or something like a story about survival, but that too abruptly crashed and burned. After that it seems to enter its final path, wherein it becomes a lot more philosophical, taking a lot of what happened in the previous arcs and taking them to their conclusion in unexpected ways. Now while a lot of small things make it seem like this wasn't planned, ultimately it does come together surprisingly well. Furthermore, the parts where everything is falling apart are probably the best and most intense in the manga because they're so different from the way such stories usually go. Because the plot has major shifts, the only character to really remain a focus throughout the manga is Buntarou. He has quite an interesting character arc, where rather than being something like steady growth, rather it's more like two steps forward one step back, in terms of where he starts and where he ends up. It also has a take on being alone that's quite a bit different from most manga, wherein it doesn't seem to try to push the message that being a loner is bad at all for the most part. This messaging about being alone and person's place in society and meaning for existence do get considerably muddled in the final arc though. Other than Buntarou and some of the characters introduced in the last arc like Hana, it seemed to try to make all the characters eventually seem like awful people, which makes sense when pushing why Buntarou needed to be alone, but as someone that's pretty character oriented I still wasn't much of a fan of this approach. In terms of the action, it could be quite exhilarating at times, but at others it felt like it was dragging on. Part of this was that while the imagery used to convey broader, philosophical elements related to climbing was really good and the did add quite a bit most of the time, as it approached the end they began being used far too much, and actually got somewhat tiring. Furthermore, the ending felt incredibly rushed, wherein how it ends isn't completely bad, but how the last climb ends is rushed through far too quickly, and the epilogue to it feels like it doesn't have enough substance to it considering all the buildup. The art was decent enough, with some of the stranger shots being especially good.