I finished Darian's romance last night. I thought it was good overall. I did like that he needed time to get over prejudices. I always appreciate a romance that takes it's time getting to sex. Even if it means I miss a Bodhi-nap.
However I did have one big gripe and one small gripe. I'll be hiding them with spoiler tags.
Overall, I'd rate him about with Verr'sza. He's not going make you go "awww" and curl infinitely on yourself until you wink out of existence, but he's worth it to keep and run through however many times. I'll definitely be romancing him again. But I did get annoyed that I had to manually set his variable to get his final SoA talk and his last two ToB talks and that annoyance could have colored my experience. (I'd be willing to concede, however, that I just didn't take 6+ hours on ToB to get those last two talks naturally)
(note: while Verr is not one of my favorite romances, I did enjoy him. So me putting Darian there is pretty good (for what my opinion is worth ) He's kind of like a good-aligned version of Verr )