Review of High School DxD
First of all, let me clarify, I'm extremely bias to enjoying this Anime. Personally, I believe DxD is a masterpiece in its' earlier seasons, I have multiple reasons for this, one of which being that I can relate to the protagonist and his emotions towards his comrades, treating them as his own family as he grows fond of them. Due to the lack of spoilers in my review, I will not share any more about this. As a 'Harem' Anime, one will expect a lot of Fan-Service, however, this works in the favour of High-School DxD, with the protagonist being a pervert, one will expectthat with power, he will attempt to do perverted things. This is toned down with the varied environments and characters he encounters, putting his safety at risk so he could protect others.
This goes into the mentality of Issei Hyoudou, where through being shunned by others due to his perverse nature, being able to be friends with a whole cast of people changes him... not so much as to change his perverseness, it changes how he views the people around him, not as simply friends, but something akin to family.
Once again, I will state that I am bias in my review of this Anime, being a humongous fan of High-School DxD for the wrong reason, where most are drawn by it's blatant use of 'Oppai' I thoroughly enjoy the genuine story and the development of the characters and their arcs, making each individual into a better person for many different reasons.