Well, since the discussion is steering towards Marineford, here goes.
The problem I have with Marineford is that both Ace's and Whitebeard's deaths amounted to nothing. It feels like the end result was set in stone and the story leading up had to be forced to fit into that mold. Ace decided to stop and listen to Akainu's words for no particularly good reason only to get himself killed. That moment is the part that annoys me the most about the arc, followed by Whitebeard flexing his strongest-in-the-world-muscles only to harm some fodders and the island. Realistically speaking Whitebeard should've been able to make a bigger impact on the battlefield, and Ace shouldn't have gotten himself killed in such a stupid way.
Looking back at the arc, I can't help but think that it was just a means to make Blackbeard relevant, and give Luffy a reason to train for two years. It would've been an interesting direction for the series had Ace survived. Now, that doesn't really work since Ace being alive would take some spotlight off of Luffy, and the story doesn't seem to do that. Sometimes I wish it wasn't like that. I have always enjoyed the little tidbits of information about the grand scheme of the One Piece world, and I definitely wouldn't mind reading a version of One Piece that takes the Game of Thrones approach to dealing with different political factions.
That's of course not what the series is about and this is the reason Ace had to die eventually. He was a plot-device to allow Luffy's character to develop. Besides, Sabo is pretty much a carbon-copy of what Ace was before the time-skip, so no harm done I guess?
I don't think Marineford was a particularly bad arc. It did move the story onwards, and was quite fun to read. We got to see characters that will appear time and time again in the story, many of whom have an interesting personality and back story. That's always a better choice than introducing completely new characters at the beginning of the arc only to forget about them entirely once the arc is done (Hody and his bunch). Not to mention that the bad guys on Fishman Island have to be some of the dullest ones ever introduced in the series. Re-reading the FI arc I can't help but feel complete indifference towards Hody's storyline.
I suggest that you go reread marineford then since Whitebeard dying allowed Blackbeard to steal his fruit and fill the empty yonkou spot and Ace dying gave Luffy a reason to tell the other straw hats not to come back until 2 years and got him haki training Luffy would have been killed by Doflamingo if did not have the 2 year training did you not see the Luffy vs Doflamingo fight? Luffy had to go gear 4 to beat Doflamingo.
Ace was replaced by Sabo he was even given the same fruit so it's like Ace never died lol.
You have people hating this current chapter go read the older posts in here so you get haters every chapter and the only reason most people did not like marineford was because the other straw hats were not in it and if they were in it they would have died since Luffy would have died in marineford if he did not get saved by the whitebeard pirates,Jinbe,Crocodile,Buggy and Law they had a hard enough time saving Luffy let alone his entire crew.