The leveling might be great but only for your first character. Having to spend ridiculous amounts of time per new character hitting cap to upgrade your Garrison is the first "gate" you will hit, if you enjoy having multiple characters.

people are blaming that on there being nothing to do. Since you have never played you will definitely enjoy it as there will be plenty to do.

They are blaming it on that because there is nothing to do. WoD cost more than any other expansion and added little content. No other expansion had that little content in the beginning and even during the expansion itself.

Someone made this post in the /r/wow subreddit 2 weeks ago. It perfectly describes what Blizzard did (or didn't) do with WoD. Seriously, just read that post and you will have the reason WoW had a huge drop in subs.

I have played WoW on and off for about 7 years and I have never experienced such..."boringness" in this game. You log in, manage your missions of your Garrison(s) and basically go offline again.

LFR is great if you do it the first time, but doing it every week is just too much hassle for little gain. Heroic raiding is basically the one thing one can do in this game right now. PvP is a disgrace, Ashran is a joke. In previous expansion I had fun leveling my characters, but ever since MoP, even that died off for me personally because Pandaria and Draenor are just soooo boring. Once again, it's great when you do it the first time but doing it even a second time was exhausting - and I don't mean it takes too long, the zones are just repetitive and boring. That's a personal thing, others probably say different things.

I honestly think that subs will rise again with the release of the next x-pac. Then they'll drop off rapidly again. It has always been like that, but now it's at the lowest point ever. And the biggest problem is that Blizz doesn't give a fuck. They put out patches way slower, they delay releases or cut stuff because they "had no time" even tho they had more time than ever for WoD.