Just finished Kenshiro's story in Fist of the North Star. I started to feel like the game was dragging toward the end, but the last two chapters were great. Ken's story is a bit on the long side; it took me around 10 hours to finish it (that includes time in menus and load screens and such, so probably 8-9 hours in reality). The combat was starting to wear itself too thin toward the end, so I started skipping every encounter I could. The combat isn't bad though and it is pretty fun to smash guys into clouds of blood, but you can only hit XXX, YYY, XXX so many times. It would've been nice if there was some more variety in the stages too. 90% of the time you're fighting in the same brown junkyard wasteland and it starts to get old. Once in a while you come across a ruined city or a castle or something which is nice, but that's like a once per chapter occurence (if that). The presentation is pretty good too. Nice graphics, awesome cutscenes, and a few good music tracks here and there (most of it is pretty forgettable though). Oh, and the death animations are fantastic. Watching a guy's head inflate like a hot air balloon, causing him to float several feet off the ground until he eventually explodes never gets old.
I guess I'll do Rei's story next. The rest of the characters only have 3-5 chapters each I believe, so they shouldn't take to long to finish.