Having finally caught up, I feel qualified to offer a general review/opinion of it.
Simply put, I love it. 9/10 easily. The art is great, the characters interesting and funny, the battle sequences intense, and the ecchi scenes sexy.
Be warned that there is a ridiculous amount of borderline-hentai ecchi scenes. It's probably the most ecchi-filled non-hentai series I've ever read. Most of the time it's just for fanservice, but it eventually gets woven into the plot via the traditional "sex magic" trope.
Nudity aside, it is a very strong shonen fighting manga. There's a lot of interesting foreshadowing early on with Kazuya's family relationships, and it eventually gets fleshed out really nicely. Some of the fighting scenes and special fighting moves rank right up there with the traditional shonen greats. The artist is really skilled, and he comes up with really interesting combat moves and stuff.
It's definitely not for everyone, but if you like ecchi and quality fighting, this is the series for you.