(This review covers both seasons as it was meant to be seen and will be on both seasons review section.)
Shinmai Maou no Testament comes to a close on this final season. I think is fair to say that it excelled as a successful "Ecchi". The Succubus factor not only delivered mind blowing fan service but assimilated well the action elements as well as to rid the common problem of the Hero vs Demon premise suffers from. Locations of peers when kidnapped as well as growth of our protagonist on a steady pace thanks to the aforementioned succubus factor.
We are left with many questions and I certainly feel compelled to check out the Light Novel. The story is standard given spice and the elements thrown by the author are very creative, Made use of many cliches and some ideas found on other Light Novels and boosted them to his advantage.
Art = 8
The art is very good on regards to the cast, not so much on the enemies. The animation was very good however it didn't steal much.
Sound = 8
The sound is very good and the OP / ED were among the best I may add.
Characters = 5
i was a bit disappointed on characters since they seem a bit robotic at times and the personality of the villains was a tad cringy.
Enjoyment = 10
Despite it's flaws I very much enjoyed this anime as a whole. The Ecchi factor which is the heavy weight on this installation came through flying colors and was done unusually and well as some high level Fan Service. If you're an Ecchi fan this is for you, I may warn you it's more extreme than DxD and not as good.
Overall = 8
8 + 8 + 8 + 5 + 10 = 39 / 5 = 7.80 rounding up to the nearest 10th. Overall 8.