We're on the cusp of World of Warcraft's sixth expansion. In many ways, this expansion feels like something that the entire game has been building toward. Tons of things that players have been wanting to see for over a decade are finally coming around:
We've finally gotten Demon Hunters as a playable class.
We're finally going into the Emerald Nightmare.
We're finally getting to wield a non-corrupted version of the Ashbringer (though this does imply that people who got it in Vanilla Naxx are officially non-canon, which to be fair we've known about since Wrath.)
We're finally going to see the Tomb of Sargeras (I'm assuming it will be a raid, possibly the final one.)
We're finally going to have an expansion in which the Burning Legion is center-stage as the main villain. Now, Burning Crusade came close, but much of our activity was split between the Legion and the Illidari (sometimes handled really poorly, like the fact that there was no clear point where Blood Elf characters realized that Kael'thas had gone evil.)
We're also seeing a return to focus on things that players have wanted Blizzard to work on, like bringing class quests back (in a big way - I don't think any of us expected class orders or artifact weapons.) Blizzard is also pushing a return to relevance of 5-player dungeons, something that they've failed to do for two expansions (well, ok, Mythic dungeons in Warlords offered good gear - my main is decked out largely in Mythic Dungeon gear - but they didn't really add anything new to the Mythic versions and we were stuck with only eight dungeons the whole expansion.)
And not only that, but we have an honest-to-Light pre-launch event. Yes, we technically had one for both Warlords and Mists, but the latter was literally just one scenario (and not even a very good one) and the former was limited almost entirely to a single zone and one short quest chain and a truncated version of one of the dungeons.
In fact, Legion's pre-launch event is in some ways a sort of soft launch of the expansion. Everything except for the invasions and the dreadlords in the capital cities is, I believe, slated to remain in-game as part of the pre-Broken Isles quest chain for players who hit 100 later or just have not been playing for the past weeks. But for most players, this will really be a fairly complex and entertaining pre-launch event.
There are a lot of reasons to be optimistic about this expansion. I'm sure that we'll find ways to complain (we always do!) but I've got a good feeling about it.