Oh, and hopefully it should go without saying but, this is a sequel! And there's a movie! Watch both first if you plan to watch this because that's what you're supposed to do with sequels! (and watch me accidentally ignore that guideline with one of the winter shows....)
K: Return of Kings
It's been a short while since JUNGLE tried to steal the Dresden Slates and not much has changed in the interim. Anna is growing into her new powers as the new Red King, Scepter 4 is dealing with Jungle's growing power that is spreading into the regular world, and Kuro and Neko just really want to see Shiro again. Turns out that some other people want Shiro to reappear on the scene again and those two will be in for a bit of trouble in the meantime....
The first season had a muddled middle but a bigger driving force in some ways because of all of the mysteries and pulled itself together at the end with resolutions, fancy fights, and the revelation that the writers had actually been foreshadowing some things. This season is much more straight-forward, we continue the story from the movie where the Green Clan (Jungle) is trying to get a hold of the king-making, strain-creating Dresden Slates and somehow this is just a lot more dull. Like the last time your enjoyment of the series will ride on how much you like the various, intersecting casts and I found the new characters somehow even more horribly cliched than the ones we already had! One of the big themes of this story is FAMILY and I think the viewer is supposed to identify with one or more of the groups and not only care about the characters but connect with them as well which just didn't happen for me. I didn't actively dislike any of the characters (although a few of them came close) but the story clearly didn't have enough story to fill the time and too much tension for me to buy into the slower moments so even my favorite characters just failed to entertain me.
The first season was a bit of a slog in the middle but picked up towards the end, here the story starts off strong and then slows until it's coasting purely on momentum and just about to stop. I'm surprised that having a more central plot seems to have been a bad choice for the story (out of the six or seven writers that make up GoRa you'd think at least one of them could do action/plot-focused stories) but it certainly was and as I said earlier, with the tension it created there was no way to have slower, more slice of life episodes that fit into the larger story. I almost wonder if you could combine the two series into a single, one cour story. I think it's just a tad bit too much story (especially when you toss the movie in) but the show has really suffered from a lack of just, stuff in it from the beginning and it's sad that the story didn't go out with a bang or a dignified landing but just, landed halfway decently and not nearly as prettily as you hoped.
The visuals hold up a bit better this time around, I remember there was a point in the first season where you could tell the production had started to collapse in on itself and there were one or two worrying moments in this season but overall it stayed pretty good! It still abused filters like no tomorrow and continued to play around with the idea of a "handheld" camera in some scenes but it also handled what I like to call "circle-panning" much better than Rokka did, it just had a better (although still not great) grasp on composition and movement. I wasn't happy with the increased amount of female fanservice however, it was jarring to see how the male fanservice was just a bunch of pretty boys looking cool but the female fanservice involved improbably pantyshots, extreme camel toe, and a bit of posing which put American comic book pin-up shots to shame. I know that some fans whine that fujoshi are ruining anime but at least they have way better taste in fanservice.
Ultimately, after this weaker second season there's not much of a reason for me to recommend this show to folks. If you like action shows there are a lot of other ones out there with flashy effects and the same themes. If you like shows about pretty boys, well there are a lots of shows out there as well, I just won't be as much help in recommending them. If you watched the first season of K then sure, watch the movie, watch this second season, but otherwise (especially with all of the spin-off materials ending) there's just not much reason to start this show anymore.