First off, Noel feels weird. The properties of pretty much all of her drive moves have changed. The timing on even simple things, like the 214A 2B link, have changed.
Noel's drive reset no longer works. This is probably the thing that I will miss most about CS Noel. There are actually three different reasons that it doesn't work, any one of which would prevent it. First, d.5C is no longer jump cancelable. Second, d.6B does not always drop the combo after j.5D. Third, Noel's "shoryu" can no longer be followed up without a rapid cancel.
I knew this was coming, but it still hurts a bit. Noel's drive reset was the only thing that made CS Noel worthwhile. It's also the only creative thing that was done with her drive chain. This is for good reason: most of the moves in CS Noel's drive chain had properties that were too similar to use creatively. This gets to the heart of why CS Noel was a crappy gimmick character, and why I'm not sad to see her go.
In CS2, Noel's drive chain moves have interesting properties. It seems reasonable to use most, if not all, of her drive moves now, instead of just stringing together the ones that do the most damage. You actually have to account for how moves will fit together now.
The other major thing that Noel has lost is Haida looping. You can still do it, but it's much harder, and extra damage scaling means that it's not going to be the damage boost it was in previous games.
That said, this game seems to have embraced the notion of the Haida, adding a run cancel to Noel's 22C (similar to the one on Ragna's 5D). You can now chain a long string of 22Bs and then continue your combo.
A major thing that Noel gained this game was a fast crossup. This means that Noel has a slightly better time opening the opponent up, one of the hardest things to do with CS Noel. Because of that, Noel has gained huge potential. She has some of the most damaging combos in the game (after Arakune), and now that she doesn't have to take massive risks to get the first hit, she can actually make much better use of them.
I haven't played CS2 Noel in a match yet. It's going to take a long time before I master her combos; she's changed almost completely from CS1. That said, I'm going into CS2 with a lot of optimism. I think Noel is finally becoming a solid, well rounded character rather than the gimmick focused character that she used to be, and I'm very happy about that.
Addendum: Hell yeah. Throw whiffing in combos is back.
Edit: It seems that I was wrong about one major thing. Haidas are back. They exist in a very different form in this game (22B > 66C and 22B > 66A), but they're there. Time to learn some new combos.