pve is really fun, mythic+ and raids are there to fill your free time. you will enjoy it (unless you deeply hate pve for your own reasons).
get a group of friends to play with and you will have fun as there's a lot of content and blizzard keeps releasing new things to keep the playerbase busy, which is a very nice plus.
pvp wise, not much has changed. some retarded comps, some retarded mechanics, some classes are superior to others. better than WoD but i still get stomach aches.
the issue with WoW is that you need to stick with some players, play with them, learn to play with them, meet up online at a specific time, queue, hope you get good opponents and teams you can beat that do not outcomp you. the rating grind is also long.
if you're a fan of the system, you will still enjoy it.
however, if you've grown up and can't dedicate yourself to the game as much as before, you might just end up wasting hours of your life queueing something that won't actually entertain you.
times have changed and sometimes i rather keep my battle net client shut down and have real fun with 1h of Battlefield 1 matches. guaranteed fun at any time of the day instead of the whole hassle with teammates, which can be very tedious