Creator Backlash: David Mazzucchelli, the artist, has expressed distaste and regret, in an afterword to later collected editions of the story, for its controversial Post-Crisis origin for Catwoman as a former sex worker. He now considers that it adds unduly sleazy and adolescent content to a genre essentially aimed at children (although this is a bit ahistorical, as Catwoman was created in the Golden Age at a time when superhero comics were intended for both a child and adult audience and often contained quite a bit of sex and violence, and she was Exiled from Continuity for much of the Silver Age precisely because she was considered too sexualised for children.)
Follow the Leader: This storyline was so successful, it kicked off the various "Year One" storylines in DC, and Marvel.
Ironically, Batman Year Two (following immediately after this story) by a different creative team) is now all but forgotten.
What Could Have Been: Darren Aronofsky and Frank Miller wrote a script for a very loose, R-rated live-action film adaptation of the comic, which was set to reboot the Batman film franchise after the failure of Batman & Robin. The executives ended up passing on the Year One script because they felt it would have been too dark and bleak for parents to bring their children to.
Said script made Bruce into an outright maniac who wrote letters to his dead father, lived out of a garage owned by a black mechanic named Little Al (the script's version of Alfred), and MacGyvered up all his crime-fighting gear from parts he bought at a local hardware store. It ended with Bruce inheriting his fortune and moving into Wayne Manor with Little Al.
Prior to that, Joel Schumacher had wanted to adapt Year One when he was brought in to replace Tim Burton, and even got Miller to help him write a draft. However, Warner Bros wanted something more family-friendly due to complaints from Moral Guardians, and we got Batman Forever instead.
The Animated Adaptation of Year One was released the same day as Batman: Arkham City, the sequel to Batman: Arkham Asylum, and shares a lot of the same voice talent: Grey DeLisle (Barbara Eileen-Gordon and Vicki Vale) is Catwoman, Vicki Vale (again), Stacy Baker, and Martha Wayne; Steve Blum (Stan) reprising the role of Killer Croc and voicing Sickle; Fred Tatasciore (Flass and Johnny Vitti) reprising the role of Bane and voicing Solomon Grundy and Mr. Hammer; and Danny Jacobs (Flass's lawyer) reprising the role of Zsasz.