Except they're not doing that. The Theurg, for example, just gets a list of the 5e spells they have access to. The same for the Ordo Magica wizards. Just a spell list from the existing spells. Feats are nowhere to be seen. It's a pretty clean direct port.
Albretorian culture isn't that different to many pseudo-medieval settings that work with D&D. The drag of Corruption on spell casting will be significant.
In play the flavour is not really from the system, it's much more from the deep lore and labyrinthine plots and intrigue.
Plus absolutely terrifying elves.. oh and rage trolls.