When it comes to Shinmai Maou, there are three main componenets, of which a novel consists: Everyday life and social interaction of out main characters, hardcore-ecchi scenes, and fight scenes featuring Basara. And many of these components is handled rather good in this volume.
The everyday life takes up a huge part in this volume, which was to be expected, since the overarching plot of the first three novels came to an end in the third volume. There is a sports festval going on in school, and Basara and the crew attend the planning committee. And I won't lie, this part was reeeeally boring. Maybe you are more interested in this sort of things when you are japanese, but I didn't see the necessity in writing so detailed about how the committee is organiszed and just what needs to be kept in mind when planning a sports festival. But as I said, maybe there are cultural things involved that I just can't see as a non-japanese.
The ecchi parts .... well. I thought they went a bit overboard in this novel. Because there is one scene that just can't be categorized as ecchi anymore, that's plain right hentai (talking about the paizuri scene as seen in the artwork). Also there is one scene that involved licking armpits and feet, and while everybody has some fetish, this is defenitely NOT mine. But aside from this two scenes, the ecchi is how you are used to it after reading the other Shinmai novels.
Now, let's go the good part. The fight scenes where pretty badass. Not only Basara gets to shine, but there is another person singlehandedly taking down a baddy with style and showing just how overpowered that person is. Involved in this was some pretty cool worldbuilding that I didn't expect to get in this volume, which is another nice point and is doing some build-up for the following volumes, which will most likely center around the conflict that we get a small glimpse of in this story. The worldbuilding in Shinmai is something that I dig. Because it is brought forward with its characters, not with its events. Now .... Basara. If you need some motivation for reading this novel, go to Baka Tsuki and look and the artwork for it. And take a look at the third to last one. That is Basara. In his badass mode. I've never seen a light novel character actually being cruel or scary or badass, but that did somewhat change at the end of volume three, and does continue in this novel. Basara is a friendly guy, but you better not fuck with him or the ones you love (literally or figuratively).
Sadly, the badass scene with Jin at the end of the previous novel, yes, DOES get to continue in this novel, but ends somewhat in the middle of it and he doesn't show up anymore in this novel, which leaves more questions open than it does answer. But then again, this will most likely play a role in the following novels, so I'm looking forward to them.