One of the most famous names in anime when it comes to the author of the source material is NisiOisiN. Monogatari is a pretty popular series with a lot of people enjoying its visuals and pretty nifty wordplay and twists in the writing. Of course when it was announced a novel from him was getting an anime covering a death battle game of course people were excited for what kind of twists could come from his mind. After episode one delivering a pretty neat twist these expectations likely grew but the problem is, that is never what Juni Taisen was about.
Early on people noticed a couple glaringly obvious hints at who would win (or at least who was going to die next) which I think added on to the general negative opinion the show started to adapt. It doesn’t help that aside from some pretty neat fight choreography the visuals aren’t much to look at. That’s the two things NisiOisiN adaptations are known for so what could possibly be liked still?
Personally I enjoyed the characters. While none have some super unique characteristics that’s the same as Monogatari and I know I’m not alone in enjoying the characters over there. So what do I enjoy about them? I just think NisiOisiN just knows how to fit certain characters into certain scenarios and make them work.
While a bad ending can affect my enjoyment of a show I’ve always been more about the journey than the ending. Applying that to a character’s life and I don’t really care about knowing a character will die. As long as I can enjoy the time the character did get on screen I’m fine with knowing their fate ahead of time. Every character gets their backstory shown and while I can’t say they were all great and I at least got some enjoyment from each one.
The soundtrack is pretty forgettable outside of the opening and ending songs. The (Japanese) voice acting was pretty enjoyable from me with no real complaints.
Overall I’d say if you go in not expecting some huge twist to be applied to the death battle genre you can probably find enjoyment (assuming you like NisiOisiN’s stuff in general) from the show. Just know you aren’t meant to try and figure out who will win.