So, yes, you aren't getting as much straight comedy in this season. If that is the only part of Gintama you like (I don't know why you would be crazy enough to only love the comedy, though), then this season veers away from that. There's only one major story arc, but all the episodes are heavy in one way or another.
The theme of this season, for the most part, seemed to be how important and precious Gintoki is as a main character, as a friend, and as an ally. This season did remarkably well to show character development for most every sector of the main cast by showing how Gintoki affects their daily lives. It was honestly really refreshing to cry more often while watching this season because the stories that are being told at this point have so much weight to them because of the history we have with the characters.
If you're wondering how the main story arc this season stands up against the rest so far, it's probably one of the better ones in terms of development of the plot and Gintoki's past. It did really well to lay out the main chess pieces in the growing conflict in Edo to help the audience understand who was important and who stood on what side. As I said, Gintoki's character also got great development through this arc.
I can't say much about the comedy this season as it wasn't as present as before. It didn't feel like another character this season but rather an element of the overall anime. If that worries you because you think Gintama should be a comedy primarily, I can assure you that the lightheartedness still lives on in this season right alongside the action and emotion, it just carries more weight with it.
The art this season was gorgeous as well, especially during the close-up shots of Gintoki's face during the battle scenes. The contrasts and details were beautiful. Another thing I noticed this season that I haven't really paid attention to in the past was the soundtrack. In the main story arc, at least, I noticed that the soundtrack backing the battle scenes had improved a lot and was lending a lot more to the overall tone of the scenes.
So, yeah, as an overall assessment of this season, I'd say it's probably the best so far. The other seasons' best parts are just as good, but this season didn't have a single episode that was moderately boring like previous seasons have had (though previous seasons have only had a handful of episodes like that). I'm looking forward to where this development will lead.
