They're okay. Not great, but playable. They run pretty poorly relative to how the games look, but any modern PC should still be able to handle them (no problems using a 1060 6GB). They're pretty basic in terms of options, but they work.
The Arland ports are the worst of the bunch. Meruru crashes on the final boss fight, but you can
get around it. Totori also randomly crashes with no way to get around it, and all three have laggy menus. I haven't personally played Rorona on PC, so I don't know if that crashes as well.
I don't know how the Mysterious DX versions are, but the originals had low res assets (from the Vita version rather than the console one), and Sophie had weird FPS drops in menus that I think was fixed with a patch. And Firis was just kind of buggy in general.
Ryza 2 at launch required a controller to be plugged in, otherwise it would stutter. I don't know if this was fixed, but if it wasn't you'll need to use a wired controller to play it.