Okay to get it out of the way, this anime is heavy on the harem which is why I would never recommend this to anyone, this is the kind of anime that you would stumble upon on your own. But having the harem in it is what gives the anime that extra boost and should not be judged for it. A show should be judged by the story and the quality of it which is why I gave it a 9 out of 10.
That being said, this anime is freaking awesome. The story does take an episode or two to get going but once it does, it is fantastic. A story about angels, fallen angels and demons, adding into it with violence and sexual content and boom you got "Highschool DxD". Along with very likable characters like Issei who's dream is to become the "Harem King", to even Satan himself, every character has a personality that the viewer can enjoy.
Now what makes this even better is that if you do decide to watch this anime and get into it, you'll be happy to know that there is a third season being developed and if you're like me and prefer dubbed over subbed November 2014 season 2 will be released in dubbed.
In all from the two seasons that I watched I am very pleased and anxious to watch the third season when it starts and hopefully will continue after that.