I actually didn't mind the Reborn ending itself. I thought Tsuna still being the same dumbass at the end was a nice change from all of those shounen endings where everyone becomes a badass.
The rest was absolutely horrid though. Soooo bad. Ugh.
My main problem was how it was set up to be this grand final fight, but... Well... It seemed like Tsuna would actually become the boss and he was finally showing resolve. Then we get to the fight with Bermuda vs Tsuna and it seems like we're going to move on to a huge battle with Checker Face. Ah, the finale that's been hyped up for so long! This is gonna be awesome!
However, Checker Face comes out of nowhere, reveals himself to be the Noodle Shop guy from the Future Arc and is a fucking alien from a race that came before humans. Oh, and so is Yuni.
What the everloving fuck? Then, out comes Talbot, starring as Deus Ex Machina, who prevents the Arcobaleno sacrifice with a "container" of fucking bullshit he pulled out his ass. The end. Everyone is happy, Tsuna doesn't become the boss, they all live happily ever after
What what
WHAT