I read the first three, and, well, they were okay. I would +1 fran_fic's review two comments up, that other than the m/m pairing there is no difference from verrry standard fantasy. As fantasy reader, I'm missing some kind of spark, some kind of original idea. There just isn't. The m/m is okay, I mean, it has some nice tropes/kinks in it that someone who reads origslash will recognize and maybe like. But other than that, it's bland as well.
I heard the fourth book is pretty controversial in some aspects, but I don't remember what exactly.