I'd hope with Zayn his label give him time to grow. If you're a One Direction fan, I can see why you wouldn't necessarily buy Mind Of Mine because it's so different but I think he made a really good album personally.
I think you can tell that it's the sound he wanted to create and I think it's good he didn't just go for a commercial, R&B sound to sell albums. The charts now pretty much consist of either dance remix/samples of older songs, piano ballad remixes of older dance songs, Drake and Bieber so I'm happy his album was a different song.
He can't afford to not promote though. I think he's done two TV appearances since Pillowtalk was released and just a load of magazine interviews. I understand his anxiety issues and how it was probably easier when One Direction were around him so he could sink into the background (which he tended to do for most of his time there).