Some things that were mentioned that I felt the need to comment on for some reason.
I don't think that Katakuri contradicting part of his personality even if it was shown just a few chapters ago isn't too crazy when it's overruled by a stronger part of his personality. Whether it's a need to be the best (A bit more doubtful since he acknowledged Luffy being his level) or wanting a fair fight with someone at his level. The reason I put emphasis on being at his level is that it doesn't matter if he's never shown an honorable attitude towards opponents before this point to fit his characterization, in my opinion. So unless some other reason is given for his behavior, I can accept the rationale in my head about him caring more about a fight with an equal than his complexes over his reputation and image.
Also, Flampe's attitude change towards Katakuri after his face reveal isn't outrageous either. Her attitude is centered on being popular. She even talks about becoming Katakuri's favorite sibling because he's so popular and thinks she'll become more popular if she's favored by him. So it makes her feelings for him was superficial. It's also not too much of a stretch that someone like that would love to tear someone else's popularity down and since she can make Katakuri less popular than her why should she care about sucking up to him anymore. The only thing off about the interaction is it could have used a panel detailing a train of thought if that was the case and she should still care because of his strength and he could kill her even if she is a family member, lol.
I think saying the fight has no meaning is too weird of a statement. Luffy took part of an assassination attempt against Katakuri's mom and captain and Luffy is fighting to stay alive. It may not have an impact on the outside world's events, but I'd say it's still far from meaningless.
For the fight being too long, I think it may be better going back and reading through it after the volume's over because stuff can seem to drag when reading from week to week. Even if it does feel to go on for a bit after the full thing is completely out, I wouldn't find it to be bad at this point. Luffy needed on screen growth after his fight with Doflamingo to start raising himself to be able to be considered a serious threat to a Yonko. I think this fight has given some pretty good opportunity for Luffy to receive a strength upgrade without it happening either in a time skip or off screen like Enies Lobby.