Now before I get into this, while I am an Ichihime fan that does not influence my opinion on the ending, Pairings are just a secondary thing, how solid the story writing is, however, is much more important.
While the fanbases opinions on this ending are pretty fractured, some saying it's a horrible ending others praising it because they got their pairing. I am gonna take a look at how the characters are as well as how events panned out in detail. as well as add some recently revealed Information from Kubo himself. this is taking both chapter 685 and 686 into account and how they connect with earlier events.
in ch 684 we saw Ywhach's final defeat, while it felt pretty anticlimactic, seemed Logical, residue left by his powers were ultimately his greatest weakness, as a Silver arrowhead created from the very substance the auswhalen left in the deceased mixed blood quincies was used to greatly weaken him enough to get in a fatal blow.
in ch 685, which is 10 years later, we see Kyouraku visiting the grave of Jushiro Ukitake, this visitation also made him late for the promotion ceremony. of which we see Rukia Kuchiki is now captain of the 13th division, and with longer hair to boot. Personally I am proud of her for this. Renji, of course, teased her knowing full well how flustered it would make her. we also see a dark mist similar to the stuff that once surrounded Ywhach, as well as Akon, now the Lieutenant of the science and developement department comment a reiatsu reading being very similar to Ywhach from 10 years ago.
in ch 686, we find out that the dark mist was a portal, that was being opened by Ywhach 10 years in the past, however it promptly closes, and the mist vanishes, we get a glimpse of the past to see an explanaition from Ywhach himself as his last dying words. we also find out Renji and Rukia are now married, and have a daughter named Ichika Abarai.
Ichigo is back home in Karakura at the Kurosaki Clinic, married to Orihime and they have a son named Kazui Kurosaki.
Yasutora "Chad" Sado is now a profesional Wrestler, Uryuu is a doctor. Most of the gang, minus Uryuu met up at the Kurosaki residence to watch Chad's wrestling match, Uryuu, having been unable to meet up with them, instead took an extra long lunch break to watch chad's match over his cell phone.
now, as for how well the final few chapters connect with the rest of the series prior.
(this is where the fanbase has fractured opinions)
While some people are complaining about not getting their pairings, I am gonna look at the history behind them.
Canonically, Renji and Rukia have a very long history as childhood friends, which upon her being adopted into the Kuchiki, they hardly ever spoke and even avoided each other. Renji even says that the one who mended their broken friendship was Ichigo. In terms of history, theirs is pretty deep
as for Ichigo and Orihime, in the begining Ichigo states that he met Orihime due to a mutual friend: Tatsuki. Rukia throughout the series had also been supportive of orihime's growing power when her shun shun rikka finally awakened, as they often would spar off in order to train. Orihime wanted to be able to protect her friends, and eventually she was given the recognition By Ichigo when they went to face Ywhach in Warwhelt, trusting her to be his shield.
as for characters, They didn't lose what made them so likeable. while matured, they still show personality traits that they have had since the begining, Yuzu still has her usual cheerful innocence, Karin is still a sharp tongued smartmouth, Rukia is still verbally antagonistic towards Ichigo, and Ichigo still reacts the same way as ever towards that antagonization. Keigo is still a perverted moron, Tatsuki as hot headed as ever. Soi Fon still has her temper and of course pride in her stealth and espionage abilities.
as for the status of the fanbase;
I am abit disappointed in some people, some IH fans are becoming overly cocky and indirectly antagonistic towards the IR fans who are extremely angry over not getting their pairing and openly hating on Kubo due to this. most arguements on why the chapters are bad aren't even good ones, just excuses out of bias anger for not getting what they wanted. and most who praise this ending also do so for all the wrong reasons.
Bleach isn't a romance series, It's an action, fantasy, Shonen. If a pairing happens in a way that fits in well with the canonical events, then it should be regarded as a bonus for those who ship it, NOT the single most important thing in the series.
(Edit)
Forgot to mention, according to recent interviews, the reason Kubo took the series in the direction he did is his way of expressing his anger and frustration towards Shueisha and SJ for overexploiting his series and forcing an overabundance of restrictions upon him.
Love what you love, ignore those who give you shit about that and Don't be an asshole towards those who don't ship your pairing!