F&F I agree with, just a complete waste of space, but Jimmy Fallon we absolutely loved - great fun, rode it lots when we were there.
Part of my complaining there is because, at the same time that UO opened those two rides (and imported King Kong from USH), Disney opened Pandora / Flight of Passage. Even in this thread, it's like people have memory-holed that Disney built and opened Galaxy's Edge while UO opened Hagrid's, which was broken for the first several months it was open. People can readily argue that Universal is coming up with great stuff, but GE was a solid attempt at letting Imagineering go big.
(At to the person lauding Velocicoaster - installing a standard roller coaster takes a lot less time to finish than any ride that includes new and different technology, which, by all accounts, Guardians does.)
I'll admit, too: I'm going a little Inside Baseball on Fallon. I personally didn't like it because it felt like a 90s CGI-heavy retread (and felt more like an echo of Conan's Late Night rather than Fallon's). But then I spoke to someone who worked on it, who acknowledged that it wasn't the ride that they had originally intended it to be. One of the key personalities involved (who I'll leave nameless) demanded a bunch of changes that diminished (in my opinion) what it could have been. The original concept sounded amazing.
I personally think UO is just "fine". I was a UO passholder a couple years ago, and just couldn't find the energy to go more than a handful of times. I have friends who specifically avoid UO because it can cost as much (or more) than Disney for a one-day ticket if you want to ride the Hogwart's Express, which is a solidly great attraction. (To be fair, a few of them have also admitted that they're getting priced out of a WDW trip.)
But I also think the whole "I'm going to Universal instead" whenever Disney does something questionable is just weak sauce. If you want to do that, fine. But it's not the threat that it sounds like it is.
I think Disney should genuinely be worried about Epic Universe - assuming UO can get it built and it lives up to the hype.
("I'm going to Universal instead" is still a better argument than the people on the DL board who reacted to DLR's changes at reopening by loudly proclaiming that they were going to Knott's instead. Not that Knott's is bad, but it's not even in the same league as Disney or USH. It'd be almost like proclaiming that you were giving up your WDW AP to go to Fun Spot.)