As it's part of a film series, ultimately this is incomplete, and the three should probably be rated/reviewed with all three parts combined. This segment is a prequel and it fleshes out Araragi's backstory, as was shown briefly in episode 1 of Bakemonogatari and in small snippets throughout.
For those who enjoy the character interactions and the meandering dialogue, there really isn't much here, other than with Hanekawa at the beginning. Most of the dialogue is expository in nature, establishing Araragi's relation to Shinobu and the development of his own vampiric powers, and the introduction of three vampire hunters whom Araragi must confront.
The main attraction is the character art/animation, and the way it all blends quite well into mostly CGI and photographic backdrops. The style is quite compelling (as shown in the great cover art and most every frame), but it's lacking in much substance. Given the Monogatari series' tendency to engage in non-stop banter, the stylistic choice of starting off with a four-minute sequence without a shred of dialogue or any explanation of what is going on was quite an effective sequence to establish his vampiric abilities with some fantastic effects animation and the most foreboding incarnation of the cram school setting I've seen in the series so far.
In truth, other than the stylistic powerhouse of Shaft's studio and the directorial vision of Akiyuki Shinbo, this looks and feels like your typical shonen anime where a young male is granted powers and has to fight a bunch of badass villains to protect his harem and his life. This is definitely not a good starting place to get into the Monogatari series.
Edit: From what I've read, many people are saying this character inconsistency is an aspect of the source material. The original light novels have an unreliable narrator, and this is obviously not easy to portray when the material is moved to a visual medium. Shinobu is featured in Nisemonogatari far more prominently than in Bakemonogatari, and she actually becomes an important character by that point, so watching Kizumonogatari before Nisemonogatari is not absolutely essential, but is probably recommended to understand the past relationship between Shinobu and Araragi, which is built upon in Nisemonogatari. So I'd watch in this order: Bakemonogatari -> Kizumonogatari -> Nisemonogatari.
