So I’ve watched the finale after being completely spoiled (thanks YouTube) and I think that:  

@Background Pony #E03D  
Except for sugarmac. That Ships pretty much canon

@Background Pony #E03D  
It’s probably left ambiguous for the fans to do some interpretations

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Big Jim pulled out of his Twitter being public due to cringy bron(ies?) threatening and name-calling him about the ending.
 
Unfortunately, as bad and stupid as it seems, it’s a sign how widespread and large the fandom actually is. You generally don’t get (small percentage) of fans acting like that unless the fanbase is pretty solid.
 
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That said, I just don’t see what’s wrong with any of the points. Sure, I dislike canonical shipping of all kinds and didn’t want them confirming anything, but I always understood that I was in a minority. Even LyraBon, Derpy and Doc, hell, I didn’t like how SugarMac existed or how it was originally handled. I think people read into it too much; they teased it without confirming. I man, the phantom is going to explode and get angry if they don’t confirm ships, so doomed if do or don’t. Best play it safe.
 
I thought Twilight’s next Alicorn phase was a bit strange but not bad. I expected that to be the part most people got upset at. Granted, I suppose they could have ended it at the crowning ceremony but showing the future was pretty well abd carefully done; it most certainly could have been worse on so many levels.

@Chopsticks  
Not saying this is or isn’t my opinion, but i will explain why some of the things you brought up annoyed people: (though i haven’t heard of any death threats)  
It was more than one loosely implied ship. There is Pinkie/Cheese, Discord/Fluttershy and Sandbar/Yonah, plus HEAVY implied Applejack/Rainbowdash. Many of these were controversial among the fandom.  
Yes, normally they didn’t wanted the villains to be reformed, but they went out of their way to build up an actual redemption arc, something they didn’t do for the others villains, and then didn’t go through with it. It’s like a slap to the face to both cheeks instead of just one.  
That Cozy was one of them was also quite…weird. When she got thrown into tartarus, everyone had a good chuckle “Haha, so they didn’t reform her and then even threw them into a prison. Good one hasbro!” but to actually end it with her being turned to stone without any sort of light of hope that she will be redeemed one day? That’s kinda messed up.
 
Again, not saying this is my opinion or isn’t, just what people were saying.(among other things)

After having seen episodes 24,25,26 can someone inform me what is this debauchery people speak of that is so horrible that Jim Miller needed to have death threats and such about?
 
What was wrong with the ending? Really?
 
The last episode was about changing friendships and implying things have to move on, change, and evolve. It was literally a perfect goodbye. They loosely implied 1 ship, and gave imagination to more without slapping a hand and saying ‘no’.
 
Most people didn’t want the villains to be reformed, and they weren’t, they were defeated and there’s been room for their theoretical return. Cozy Glow was ‘executed’ on screen; that’s awesome; we’ve moved forward with an unsuspecting villainous child which is extremely rare in any form of entertainment. Children are evil; give them the right time, place, and capacity and they will exercise it.
 
Starlight didn’t turn into an Alicorn, which was to my knowledge the biggest fear.

@Kibate  
@Background Pony #2081  
they don’t suppor any ship. they do if for friendship between these characters.

@Background Pony #2081  

 
You do realize, that stuff like that is decided by an entire team of writers, directors and producers, right? The writers only decide on how the details of an episode plays out, but everything else is agreed upon in a meeting

I am so confused about this

That’s how the Pendulum swings.

@Background Pony #54DE  
It means it’s his personal wishes and doesn’t change anything since he doesn’t write scripts.

@Background Pony #7BD4  
So in other words it’s for interpretation then?

@Background Pony #54DE  
It applied to Cheese and Pinkie and Lyra and Bon Bon. As you can see, this mean less than the opinion of any brony under Equestria Daily comment section.

So what Jim miller said about fluttercord also applies  
to Rainbow Dash and Applejack?

@orbsah  
If you wanna talk about about ships and romance in its entirety done by Haber, then episodes like Simple Ways and Dragon Dropped are a better examples to this. He tends to write romance stories in forms that’s already been done before and used to death in other old cartoons that it comes off as predictable.
 
Case in point, once he comes up with an idea for an episode or story he never goes further with the idea nor adds his own original style to it which results in his writing being bland and basic. If anything he just goes by the book and nothing else, which makes most of his writing lackluster.

@LightningLazer  
But the topic is ships he written about.

@orbsah  
It’s not romance that’s lackluster, it’s Haber’s writing.

@LightningLazer  
What is lackluster about romance?

@Background Pony #2081
 
@Background Pony #2081  
This is actually one of my problems with Haber’s writing, it’s lighthearted but lackluster and if this how he does things then he’s better off writing more simple slice of life episodes than a proper story because when he does that …he fails.

@Background Pony #E03D  
Cause he didn’t write the episodes. Josh did! Pretty much every canon or implied ship this season was made by Josh!

If he’s not interested in romance, then why did he make Fluttercord, Cheesepie and Sugarmac canon?

@Background Pony #7BD4  
An obssesive shipper will talk about cringe? Ok