A big high of this year, which I touched on earlier, was the different wrestling companies on TV. If you are able to get all those different networks. There was ALOT of variety this past year. NXT, ROH, Lucha Underground, TNA, and WWE (RAW/SM). Which is great for a wrestling fan and it looks like all will have a home somewhere (looking at you TNA) on TV in 2016.
Disappointments of the past year, besides all the injuries in WWE/NXT. Would be the Diva's Revolution, TNA (as a whole), Wrestlemania, Undertaker's 25th.
Highlights of the year (sure I'll leave some out): The NEW DAY, Kevin Owens vs. Cena matches, NXT woman's championship matches, Rodrick Strong vs. Jay Lethal matches, Davy Richards vs. Eddie Edwards, and the Trios championship matches.
I won't go into great details about each of these matches/rivalries or wrestlers, cause it would make this blog WAY too long. But all of these are great examples of pro wrestling done right.
Even with the highs and lows of the year. I'd say that 2015 was a very good year for wrestling. Despite injuries and disappointments. 2015 had great female wrestling and "indy" stars that were able to showcase their talent in multiple wrestling companies on TV. Which will hopefully make those stars household names. As they say "history was made" and I think the history of 2015 will be talked about for a long time.