If you don't like the relationship between Kojo and Yukina, it doesn't change. Drop the anime. I really don't like to drop anime because usually there are redeeming qualities and I want to know how everything plays out. But in my opinion, their relationship really is a deal breaker.
Otherwise, this is going to fit the bill of your other "powerful protagonist series". I enjoy these kinds of series, and excluding Yukina and Kojo, this would have been no exception. Kojo is cool, there's action, excitement, I definitely feel like the plot/whatever is original enough, and it's enjoyable. Something I would want to watch.
If you don't enjoy the powerful protagonists, and you don't enjoy Yukina, then definitely don't watch this anime. If you just don't like their relationship, I really wouldn't recommend it, I would just drop it. Otherwise, this is a really solid show to enjoy watching.
As a final note, WOW, the front page reviews are novels. If you'll just trust me guys, really, it's simple.
