I disagree about both the disadvantage and neutral, though I am pleased to hear that her results are better than I would have thought they'd be. I am aware that some people are making her work, and I had pretty decent results myself this weekend, but I really don't think she's proven herself viable compared to the top performers and I don't think she has the tools to get there.
I do think her disadvantage is bad. Not horrible, but bad. Warp keeps it from being horrible. But she has a bad air speed/fall speed, she's a big target, and she lacks quick aerials to get her out of bad situations. Nair works sometimes but you often get smacked for landing it too close to the ground. Fair can work with the right positioning but I personally haven't found it reliable. Unlike most characters with reflectors, hers is bad when coming down as charge shots and such can sneak in underneath. She has a counter, and that's nice, but it's terribly slow. Everything about her disadvantage just screams unimpressive to me. Her best tool is for survival only, and she has very little realistic hope of turning things around until she can get back to neutral.
...which I do think it quite bad, too. Bair is a great tool, and don't let anything I say downplay that. Bair (and to a lesser extent, dash attack) is one thing that -does- set Palu apart from the crowd. Other characters wish they had an option that could just fearlessly challenge another attack like that. But I don't think it's as safe as you're saying. It has 16 frames of landing lag, from the moment you hit the ground, and while it's range is good, it's not immense or anything and there are a number of characters that can dash attack it or other quick moves with some kind of range. Fair is a passable tool. Jab is a good move in a vaccuum and sets up for great damage but I'd rather, numbers wise, the move was on Dtilt or Ftilt or something and we had a faster move assigned to jab. since we're not really left with any options when up close against Luigi/Zamus/Mac/Falcon etc. etc. Dash attack is slightly better than your average dash attack and not very special compared to the best dash attacks (MK/Falcon etc.) and while it's our fastest grounded option, it's a scary move to whiff
It -is- hard, and that's what makes her unviable. To beat someone with Palutena, you have to either be soundly outplaying them or get a lucky uair during the Delfino transformation. There are no freebies, there are no situations where she dominates other characters. She has to win with clean honest hits and reads, and in a world where Luigi gets half a stock off of a grab and Sheik wins neutral by smashing her face into the controller I just don't think it's enough to compete. I do believe that high-placing Palus are outliers and that the character is not doing these players any favors.
She's pretty good against Villager though
Again, if you like Palutena and just want to play her no matter what, go for it, Shoot for the stars, see how far you can take her. But if you're looking for a competitively viable character to win tournaments with, look somewhere else.