Context: I've been playing a lot since BFA and also raided semi-hardcore in classic all the way up to mid-Wrath. I do heroic raids and plenty of m+ every season while also collecting stuff and doing plenty of side content in the open world.
So far in the first week of launch, it's been pretty much the usual WoW expansion but a bit more, including:
1) 4 new zones which are incredibly spacious with lots of open world
treasures and rares that actually give meaningful rewards
2) Account wide rep gains which give you a reason to do the local
stories that people usually skip over, encouraging more world
exploration
3) Dungeons that aren't mechanically obnoxious or take forever to do
like brackenhide hollow or nokhud offensive
4) Delves which are basically solo (or group, your choice) dungeons except you no longer need to rely on getting overpowered upgrades, dying (you have infinite unpenalized respawns) or have to worry about clearing fast like in torghast. They aren't even mandatory either, just another option for players to quickly get some competitive gear to start on their m+ or raiding journey.
5) Hero talents which vary from being passive but having noticeable effects or grant you a completely new ability to play around. As usual, some will suck more than others since 30 new talent trees will obviously be impossible to balance perfectly.
That being said, some quick cons are:
1) The leveling experience was way too easy because of broken scaling, providing basically no challenge at all. Blizzard supposedly addressed this issue but I have not tested it yet but regardless, day 1 leveling was basically gathering quest mobs and AoEing them down in braindead fashion.
2) Probably the most important takeaway is no, this is not a return to the classic-y era of WoW of grinding for attunements, building open world connections with other players, or taking 30 minutes to travel to a dungeon entrance or do to basic activities and the game will never return that way because of the nature of gaming retail has housed for almost a decade. War Within is simply the previous few expansions except much more alt/casual friendly. The formula is still the same, 80% of the content comes at max level in the form of high tier delves, raiding, m+, rated pvp, or completionist activities.