I will comply my feedback once I finish my playthrough but early impressions: (mods, you can ignore that feedback for now.)
Reactions are really confusing. Most of them can't be used through the new system, so far the exceptions have been: smite (which isn't a reaction) and bardic inspiration (you cast it on character as you used to, but then can trigger to be asked to use it). But attack of an oportunity is still automated, and can be set to trigger during that character's turn only - I would assume that they just didn't get around to implimenting old reactions into new system, but then I picked raction on Paladin that allows me to protect a nearby partymemeber and it is also fully automated. I really feel they should compile them all into one UI and let us set everything as we wish. As it is not, we have two seperate UIs for reactions (not counting popups) and different reactions can be found exclusively in one of those two UIs, and some of them aren't even reactions.
I think their idea is that reactions that don't consume a resource - like spell slot or bardic inspiration - are not worth micromanaging. But reaction action is also a resource - not that important perhaps if we have only one reaction we can trigger, but as levels pile on I think I will want to be able to choose.
