Just because WoTCs adventure paths are getting trashed in this thread in general, I just wanted to add my perspective to the mix. I think I'm the target audience they're trying to hit, and they're nailing it.
I've been tabletop gaming with some combination of the same group for 23 years now, since middle school, but we barely touched Dungeons and Dragons except when we were just starting out. We played a bit with our parents, but we got into D6 Star Wars in High School, and stuck with that for a while. As a DM, I didn't like running 3rd or 4th edition, I found them too clunky- so, we had a soft spot for D&D, and I always kept an ear open for what was going on, but we stuck with D6 Star Wars, Adventure!, Mutants and Masterminds, and various homebrew stuff. (Except for a return to 2e so I could run "Ravenloft" for everybody.)
Growing up, we'd always heard about Tiamat, Beholders, Demogorgon, Acecerak, etc. from our parents, but we'd left the game before ever really getting high level enough to deal with it, they were like these mythical things we were just sort of aware of. Now, 5th edition came out just as a long running campaign wrapped up (a five year game I ran based on the Dark Tower novels), and it was finally a system that I liked running! It felt smoother, it's got enough complexity to keep my rules lawyers players happy but my story-based players aren't overwhelmed, and the plots are letting us take in experiences with these epic monsters that had always been to the side. As a DM, I also love it because it's pretty easy to convert older material, so I've got a wealth of D&D stuff to use to punch up the modules- I started a thread a while ago about adding 4e and 3e adventures to the Tiamat campaign.
Yawning Portal let us finally try our hands at the "Tomb of Horrors" that we'd always been aware of- it ended in a total party kill, my players are itching to get revenge against Acerak, and now they're handing us this campaign to let them take him down a peg.
I know it probably doesn't seem a fresh to people that have been active in D&D specifically all this time, but I've never been more jazzed for it. I am dropping so much cash on campaign books, supplements, miniatures (We haven't used miniatures on the table in 20 years!). So, I did just want to give firsthand evidence that what they're doing is working like gangbusters to certain segments.