Yeah, if anything Quinns thought the exciting bits were all in the app.
I’ve watched a playthrough of the first mission, before the review hit, and I can safely say I have no interest in paying $160 for the gameplay on display. To the extent it’s interesting, and that’s not that much, it’s interesting like a CRPG. But I have loads of those, for much less, and they don’t take up space on my shelf or make me mess with dumb 3d terrain (apparently people are very excited by that part but for me it just looks like a colossal hassle and does even less for me than minis!). And most of them are set places more interesting than Terrinoth!
Or, for a lot of people, a mountain of great that you will probably struggle to finish, versus a smaller selection of move up and attack twice. 
For me that’s an easy choice, and it wouldn’t be Descent.
Nah, from a one vs many perspective they’re very similar, just Imperial Assault is better balanced (not balanced, better balanced) and corrects some of Descent 2e’s flaws. They both have a bunch of narrative and I think similar length campaigns, and the expansions add more stuff and more missions. You probably see more people talking about Imperial Assault’s expansions because it’s Star Wars and they add famous stuff from the franchise, whereas no one cares about Terrinoth except like one dude in management at Fantasy Flight.
Personally, I’m not sure how available it is, but if folks are looking for a richer pure coop fantasy crawler (as opposed to one vs many, where I surely have not encountered one better than Imperial Assault, but…in fairness, I don’t like one vs many much so I haven’t gone out of my way to try), my next recommendation after Gloomhaven would be Middara. We’re in I’d say the third major story chunk (not that deep in but many hours still) and every mission has been satisfying and had memorable twists, and there’s a lot of flexibility in character building and tactics during play. With the promise of much, much more as we get deeper into the campaign. Just…be comfortable with a lotta text or using the “Spark Notes” booklet to get the gist. And it being very anime/JRPG.
After that, I personally prefer Sword & Sorcery to Descent, and certainly to this incarnation of Descent, but I don’t think there’s nearly as much space between as there is between Descent and Gloomhaven or Middara.