I've been using a lot of sideB, it does fill a lot of holes. It's only safe if you hit with the tip of the sphere (tested against Sheik), but in the end you are still giving them a free approach so not great. Use it as an anti air only i m o.
Lack of lasting hitbox has always been a ZSS issue and makes punishing spotdodges/rolls hard, but at least we have a job this game. Holding A has been helping me out.
DownB being better does help with out landing game. Read Zair CAN be dashed into and FF Nair too (though ff nair is harder), but paralyzer can help with that and just downBing away instead resets the situation.
And honestly, dealing with shields is also less of an issue with rolls being better. It's a matter of being calm. Shields often make people feel like they have to answer it, but walking away and charging a dsmash or ftilting is often fine. If people shield when you dash at them, just grab. If they spotdodge, pivot grab (beats spotdodges as you slide as such that the grabbox hovers over them for a long duration, effectively giving you a meaty grab) or run past pivot ftilt. Really though run past pivot ftilt is godlike.
Well, that post was all over the place. I guess what I'm trying to say that is, like in brawl, she has issues with shields, spotdodges, rolls, and safe-on-shield moves. However, just like brawl, she has things to deal with it. When I started out and people didn't know how to play ZSS, I felt like she lost that awkwardness, which I didn't like much. But she still has it, and I'm a fan tbh. I'm getting closer to cracking the stupid Sheik matchup every time I play Mr R and I'mma try to do the same with Pikachu and Ness.