I've been playing WoW for a little over ten years now. There have been two times when I played anything like a significant amount of PvP. I did some on my Rogue in Burning Crusade to get the "welfare epic" daggers (this was a time when it was considered a lot easier to gear up through PvP than PvE) and then for a time during Wrath when Isle of Conquest came out and I wanted to try it out on my Death Knight.
Beyond that though, I really haven't done much.
Now partly that's philosophical - I enjoy cooperative efforts more than competitive ones. When you beat a tough raid boss, everyone's celebrating. There's no one behind the computer on Ilgynoth who's feeling disappointed that he got trounced.
But a big part of it was also that it seemed like you needed to be really into PvP in order to get anywhere in it - it wasn't something you could just hop in. There was separate gear you needed and a whole different set of skills you'd need to figure out.
In Legion, the new Honor system has really transformed things.
With your regular talents all geared toward PvE, the more utility-based PvP talents simply get activated when you're in PvP combat. And it doesn't take a terribly long time to get at least the first column of them unlocked.
Player power is flattened - there is a standard set of stats for all classes, and your gear can simply raise that by a very small percentage - like 5% at my current gear level.
Also, because that first column of talents is not terribly hard to attain (a lot of PvP World Quests don't actually require you to fight other players, so you can do those to get "leveled" up) and subsequent talents simply become new options in existing rows, you can pretty quickly get yourself to a point where other players aren't really strictly better off than you.
I also think that damage-&-healing-to-health ratio has been balanced in a decently fair way. Players aren't going to one-shot you, and in a one-on-one fight, both players will have opportunities to try out some moves. On my Demon Hunter, I try to hit fast and hard, getting a bleed on them and slowing them with Bloodlet (a PvE talent) and using mobility to frustrate fellow melee attackers. On my Paladin (he got his corrupted ashbringer skin finally and so I figure his longstanding aversion to fighting the Horde is breaking down as he becomes a little more consumed with a desire for righteous vengeance) I'm basically an implacable angel of death, making heavy use of Justicar's Vengeance and the 5-HP-generating Wake of Ashes to hit hard and heal myself up. And if a group tries to swarm me, I pop Shield of Vengeance and usually at least one or two of them really regrets it.
I imagine some people will complain that their gear is not providing them with the boost that they used to have, and to be sure, PvPers aren't getting the most amazing gear - the Gladiator sets this time around are 840 by default, which is on par with Mythic Dungeons.
But I think any sort of player-versus-player gameplay really benefits from having an equal playing field. Certainly more experienced PvPers will have the advantage of knowing better ways to counter their opponents, and in fact, the stat-flattening will prevent some mythic raider from waltzing in and squashing people who play mostly PvP.
Now, I'm sure that there are also reasons beyond what I've thought of that veteran PvP players might not like the new system, but as someone who kind of hated PvP for the last decade, I've got to say that I feel like I can actually participate and even contribute now. And I'd call that more fun.