Bakemonogatari was a unique show with lots of mythology and very unique and interesting characters.
Nisemonogatari was a sequel that introduced many new unique characters and provided lots of fanservice.
Nekomonogatari was a show simply about character development.
And finally Monogatari Series Second Season somehow managed to get all of those inside of it plus more.
While retaining it's style, it's perfect visuals and great direction, Monogatari Series SS has developed it's characters much more than the other three previous installments.
That whole concept of Hanekawa dealing with it while having a shit load of stress bulid up inside her enough to create darkness in he heart and monsters, Nadeko, who has been dealing with being in love and not having any response so much that she went batshit insane, especially Nadeko's arc was beautiful because of her dialogue with her imaginary god, it's all very nicely paced and makes you want more. It's enjoyable to see that she became so crazy, how she drove herself to creating darkness and accidently becoming a vessel for god through self-delusion.
Hachikuji Mayoi and her understanding of the death and life concept and how afterlife has affected her, her arc also overlaps with Shinobu's thoughts during Bake and catches your interest through this "what if" storyline, also gives some development to Kisshot Heartunderblade version of Shinobu and her relationship with Araragi and the nature of these evil spirits overall too. Shinobu's arc itself is an interesting story, but kinda lacks symbolism, 2deep4u meanings and other things that make other arcs so great.
Disappearance of Hachikuji and that atmosphere of mysterious Ougi and how she is connected to all of this is very interesting.
Then there is the final arc called Hitagi's end which gives us more Senjougahara and how she was trying to deal with Nadeko's death threat to her and Araragi through contacting her old enemy. It's because of how well written Senjougahara's dialogue is, she feels like a very realistic Hard-talker, and the visuals, the soundtrack and the dialogue between her and Kaiki make it probably one of the most memorable scenes of the last arc.
While i still felt all the arcs were a little to dark for my taste (Hanekawa's mental problems, Nadeko becoming an evil god because of unrequited love, Hachikuji dissapearing, Kisshot destroying the world in other timeline because she wasn't wanted, Kaiki's death even though he is an antagonist, but still is probably the most unique character in all of the Monogatari installments, mysterious Ougi manipulating things behind the scenes) i still enjoyed the tone change from Nise, while keeping fun and fanservice in (Senjougahara and Hanekawa's shower scene, Shinobu and Ononoki with Mayoi harem scene in Shinobu's arc and other things like that.
