Bakemonogatori is trashy, lowbrow comedy, partly deeply philosophical. A good drama to boot. Harem has a reputation for being dreck, but this is one of the best shows of its generation. To start Araragi is an MC with a personality! A rarity. He is rational, and in command. An all around "nice guy" but with oversights and flaws that make him human. This depth of writing does extend to each girl and the only other male character, Oshino (a Supernatural consultant).
Stylistically flawless. A surrealist veneer of visuals and audio to keep it interesting. Camera shots swivel instantaneously, and the eye to detail breathes the show to life in contrast to its overtly simplistic setting with nonexistent cars or humans. This is done to strengthen a core storytelling mode of this show. The main mode of story is longwinded conservations. There is action, but it's placed carefully. This sounds boring but it's the opposite. Dialogue is a mile a minute, be alert with your subs.
Each section of Bakemonogatari is dedicated to a different supernatural case. In this, we progress the story and introduce new characters. The show never overwhelms you and absorbs you in its dense universe. Conversations are highly lucid, and contain wisdom. Bakemonogatori has a playful, reference laden side, but a foothold in life's realities as well. These characters have endured hardships and many moments of hopelessness. So don't watch if you expected something idyllic. This is pretty dark at times. Not too R-rated, but an adult bent for sure.
Anyways, my only complaint would be some fairly regrettable fanservice elements but you can always skip past that and that comes standard with most harems anyway. Rewatching after 2 years only confirmed how well this has aged since 2009. It will continue being just as good 10 years on.