The only thing worth watching after the ladder match is Lesnar/Goldberg and The Undertaker's send off.
I'd say you still have to watch the whole Reigns/Undertaker match, at least I'd feel I owed to myself to see it. But I'd prepare myself for how sad it was it watch unfold. They were just kind of in there doing moves, and some of them not really that well. Reigns doing the spear through the announce table I think will be the only thing I'll remember from the match that was good. Otherwise, Undertaker almost botched a Last Ride, couldn't get a reversal near the corner out of a tombstone, and had to redo the finish because he got in the way while Roman while he was running the ropes, while ultimately made the finish a bit flat. And an exhausted crowd didn't help. But then of course there was a pretty poignant send-off. I don't know, if you don't watch the whole match, it would be like watching a TV series that you stuck with (or, in 2017, caught up on) and then never watching the last episode.
A huge thing that hurt it was there wasn't the build that it should've been. Like, it would be fine if that was at Summerslam or something, but this is Wrestlemania, and it was a watered down and rushed alternate script of Shawn Michaels' retirement. I never really bought the intensity, and the parts that we were sold to be intense seemed too manufactured. This was the freaken Undertaker's last match, the greatest gimmick and character they probably have ever had, based on longevity at least, and everything was done just to have this match to say they had it, not to really get a story over. Cena/Undertaker may have went down that road, but they were setting that up in November before pulling the plug.