The Monogatari series is huge, both in popularity and in sheer scope (over 100 episodes throughout a bunch of standalone seasons and super-seasons). Whenever I recommend it to someone, the first question they typically ask is something akin to "What genre?" I never know what to say. Defining Monogatari is easily the most difficult act of pigeonholing I've been tasked with. It's a ghost story, with a few gory bits, but its also a harem comedy, but monogamous and without the sex. It's slice of life, if your life includes vampires, demons, and ghosts.
Ultimately, Monogatari is a pastiche of anything and everything, balanced in a manner that approaches perfection. The characters are funny and three-dimensional, the conflicts are harrowing, the dialogue is funny and engaging, and the art is the most aesthetically pleasing I've encountered in all of animation. The background art alone could be in a museum.
The story revolves around Araragi Koyomi, who was bitten by a vampire, but acts like it was a minor inconvenience. Shortly thereafter, he repeatedly deals with the women in his life (as well as some who just barge into his life) being possessed by malevolent spirits that are animal-like in nature. Crabs, monkeys, bees, cats, and a snail. These animals embody the girl's personality and usually some accessory they have. For example, the best girl, Mayoi the snail, has a big, snail-shell-like backpack and pigtail that resemble snail eye stalks.
Nailing down what makes this program so good is very difficult. Everything, from the pacing to the artwork to the overarching plots that tie into one another like an intricate series of knots...it is just so terrific. Fans of shonen, slice-of-life, supernatural, mystery, and comedy can all find common ground in this bizarre mosaic of meta-humor and intense action. One minute Araragi is having a cute conversation with a friend, next minute, she's a monster who wants him dead.
As anyone familiar with my reviews, I'm a sucker for pretty animation; and there's fewer things that catch my attention more than clean lines, crisp saturation, and bold colors. But even if this series was scribbled like Brendan Small's signature work, I'd still probably put it on my top ten cartoons list. Combine that with the most detailed and gorgeous imagery, and I'd have to say this is likely my favorite animated work, that includes Western animation and films from both sides of the globe.
Give this series a try, and attempt to watch it in either chronological or (even better) broadcast order, as both vary tremendously. If you don't like it, I suppose there's no accounting for taste. Also it means you don't have taste and I hate you.