Yeah, the downside is that his Usmash lacks that horizontal hitbox, which makes it more of a true anti-air and less useful at the ledge. Although, apparently reverse Utilt consistently autolinks so that makes another work around for bad programming.
With its high active frames, it's still useful for covering ledge getup and out of shield Up Smash probably works for ledge attacks. It's just not good for ledge rolls compared to Smash 4 Up Smash. Maybe it could work if you use Up Smash facing away from the ledge, but then you lose being able to cover ledge getup and ledge attack because of Ultimate Up Smash's much shorter horizontal range.
As an anti-air, I think it's a better "opponent is above me" anti-air compared to Smash 4 Up Smash being more flexible in catching people above, below, and behind. If Smash 4 Up Smash was a circle, then Ultimate Up Smash is more like an oval with the lengthier side pointing up. In that regard, I think Smash 4 Up Smash is a better anti-air because of its coverage compared to Ultimate's. Vertically is where Ultimate Up Smash wins not just in reach, but I also think because of how long its second hit lingers above him. With Smash 4 Up Smash being a front flip, Falco's always in motion leaving less time for him to linger which would be weird. That said, because of how long the second hit is active and him slowing down a bit near the end, the second hit does linger behind him a bit. In Ultimate, it's two high kicks where the second kick begins on frame 13 and on frame 14, he's already kicking above him. The 4 remaining active frames have to be somewhere and Falco barely moves his leg after frame 14. If frame 14 is 12 o'clock, then frame 18 is like 11 o'clock.
Utilt's first hit sends the opponent into Falco, so hitting with the front or back should work. In both Brawl and Smash 4, it has three hitboxes of 100 degree angles where Smash 4 has one that is 106 and both games also have a fourth hitbox on the first hit that sends the opponent straight down, 270 degrees, to pull them into the second hit. It's only when you're clipping with Utilt or hitting at odd places that Utilt's second hit will whiff. Utilt is also another option for ledge getup as it has high active frames.
Also, if you want to see some Falco Up Smash anti-air shenanigans, Lunamado abused it against Rido's Link several times.
11/29/2018 Edit: As with 1.1.4 Smash 4 Up Smash, the new Up Smash in Ultimate has leg invincibility for all its active frames, but where it lost in horizontal range, especially behind him, I think it's vertical range is much higher since Falco jumps up more than in Smash 4. Animation-wise, like other most other moves, it keeps his hurtbox away from his hitboxes. In Smash 4, Falco's body was mostly below him during Up Smash while in Ultimate, it looks they kept his body behind his kicks. Both moves do start with Falco turning and leaning his body towards the ground before doing a frontflip in Smash 4 and a jumping tornado kick to roundhouse in Ultimate, so it does have some low profiling. Anyway, Ultimate's Up Smash is probably just as good of an anti-air when used below people, but it hitting higher means it would probably let it catch people faster than Smash 4's Up Smash. Do keep in mind that Up Smash has to make contact with a hurtbox, though, so against moves like Ike's Nair which has good coverage around him, Falco might get clipped by it.
A recent video of Lunamado's Bowser and Falco vs. Rido's Link had Lunamado anti-air Rido's Dair several times. I'm guessing Link's Dair doesn't have as large of hitbox as in the previous game, but if you slow down the moments where it happens, you can see Falco's kick bypass Link's sword.
In the second round, the first time it occurs, Lunamado catches Rido trying to land with a Dair with the second hit of Up Smash and takes Rido's stock:
https://youtu.be/Vstj4iIbc_E?t=295.
The second time it happens, Lunamado catches Rido trying to land with a Dair again with both hits:
https://youtu.be/Vstj4iIbc_E?t=420.
In the last round, Lunamado catches Rido trying to Nair:
https://youtu.be/Vstj4iIbc_E?t=482.
Speaking of animations affecting hitboxes and hurtboxes, Kurogane Hammer posted a side-by-side comparison of Cloud's Nair animation in Ultimate compared to Smash 4.
There was a problem fetching the tweet
Now I'm wondering about Fox's Up Smash since it does have a new animation or at least the end of it is different since Fox's does a three point landing instead of just landing on his feet like in the previous games. People keep saying it has more horizontal range which could be it having larger hitboxes or it could be that the new animation has Fox kicking out further. These outlier things with Fox's air speed increase compared to the rest of the cast and 1 more active frame for his standing and pivot grabs makes me feel suspicious that the developers want Fox to be really good. Also, if it wasn't mentioned already, but Fox's dash attack in Ultimate has 4 less total frames because reasons:
https://docs.google.com/spreadsheet...nf1GGIteH35UX3IM7-mnbdG6eE/edit#gid=144709605.
Smash 4 dash attack had 35 total frames to Ultimate's 31 and it has the same frame 4 startup and same active frames for its clean and late hits meaning its recovery dropped from 21 frames to 17. As if Fox's dash attack wasn't already good. Meanwhile, Falco whose dash attack gained doubled startup in Smash 4 still has essentially the same recovery since Melee, but without IASA. Melee and Brawl Falco's dash attack had 23 recovery frames to Smash 4 and Ultimate Falco's 22 frames. With IASA, Melee's drops down to 19 and Brawl's drops down to 18. Salt aside, I believe it was mentioned, and noticed early on too, that most dash attacks received buffs in some way except for some characters like Marth's was unchanged.
definitely does struggle to kill a bit, although that's not new to his character, but from watching KEN, I don't think I've ever seen Homing Attack follow-ups before. So many Spin Dashes into Homing Attack just work now for racking up damage.