I thought it was a really good Mania overall but obviously some things I didn't like. In terms of matches and outcomes, the biggest one is the end. Why have a wonky finish be the final thing of your show? That's dumb and undermines the match.
Beyond that, WAY WAY WAY WAY WAY too long. Seven and a half hours for a wrestling show is NUTS. Having people sitting in an arena for as long as they'd sit at their desk at work is STUPID. And you could EASILY cut a LOT:
-Cut the pre-show down to 1 hour. Cut both battle royals.
-Cut HHH-Batista from a 25-minute match to around 10-15.
-Cut Styles-Orton from the show
-Cut Balor-Lashley from the show
-Cut Reigns-McIntyre from the show
That's like, 2 hours worth of material right there, and you lose nothing of any real significance.