Pit's really fun. I think he's still a solid character, mid-tier.
I started messing around with him about a week ago, and from what I gather, he can literally still do all the combos he could do in 3.02, they just require much more skill and accuracy now. Fair is kinda weird, I agree, but Fair juggles into the blastzones can still be done. They just require knowledge each character's particular fall speeds and weights and what percentages the juggles work at now, instead of the Fair juggles being a more "works on everybody whenever" kind of thing in 3.02.
I think both the strength and the sweetspot of Up-B were a taaaaad bit too nerfed, but the Up-B combo finisher is definitely still there of course. I saw a lot of people in here say they're having trouble doing the Uairs into Up-B; you just gotta make sure you use Uair earlier now to hit them with the later/last hitboxes, but I'm sure most of you have figured that out by now. Raw sweetspot Uairs aren't gonna do it anymore, the timing is more strict, but it's still there.
His dtilt is horrendously slow now, yeah, so you have to combo into it now. Glide-Attack Nair -> Down Tilt is a thing, and is craaazy good when you push them to the ledge with Nair, then meteor them off-stage with Dtilt. I can pull it off kinda frequently. It's also very good for Nair -> Dtilt -> Jab reset on fast-fallers.
Arrows are.....ok. But I think they should be just ok? I dunno. I'm no Pit main so I don't necessarily know how important they are to Pit's neutral or gameplay as a whole, but eh. They serve as good pokes and can still take jumps of course so they have their uses. You just can't combo with them silly easily like you could before.
Overall, I do think he was nerfed a TAD bit too hard, but just a tad. Unlike other characters.....his identity is still there and his capabilities are still there. They're just harder to access/achieve.