The concept remains the same as previous seasons. A mini story unfolds in each episode, someone typically, but not always, gets mad enough at someone else to want to send them to hell. There are a few exceptions in that if it isn't due to anger, it tends to be a more sad reason. I also would like to emphasize that the "sexual" tags are purely due to a few actions of a single episode, as that is what the theme revolves around. So no, this isn't a sex themed season or anything.
The season is split up into 2 segments essentially. The first half has become modernized, the topics and tools incorporate a lot more of what you might see today, along with the art style being a bit more updated. The last half takes on its retro feel, going to a more classic feel and art style. This was a pretty good move, as it keeps the season from feeling too repetitive, due to the naturally repetitive design that almost each episode follows.
Something that is changed a bit from previous seasons is that there is a bit of a carry over between the first half of the episodes in the form of a mini background story involving a few characters. It doesn't add much, but it keeps them feeling a bit more connected to one another. For the most part though, the season retains its episode based nature, so don't expect any new direction in terms of story.
The mini stories for each episode are what you'd expect. How much you will like these will be directly related to how you felt about past seasons. They all feel unique enough, and don't seem better or worse than any of the episodes from previous seasons. Most follow their standard routine - follow characters, watch the conflict, insert Enma Ai with her classic speech, and watch the hell scene unfold. A few episodes don't follow this format though.
It was interesting to see the art style split 50/50. 50% being modernized, but still retaining that color and style, and the last half using the style you know best.
I quite liked the retro half, not only for its classical art, but the opening theme for the last few episodes was nice, and had that early 90's nostalgic feel. Those who grew up during that era will be able to appreciate that conveyed feeling.
As always, you got the standard Enma Ai group cast, along with many others you will only see for the single episode they appear in. Nothing changes really, so you can never get attached or connected to someone, but everyone should be familiar with that.
Overall, I liked this season a lot. It was nice to see it come back after being gone so long. Splitting it 50/50 of old and new was the right move to make to prevent it feeling boring or repeitive. If you liked the previous seasons, this one is on par with them. That said, if you didn't, there isn't anything really new here to change that.
