Evolving as an artist can be very tricky: you don't want to abandon the personal flourishes that made people respond to your early work, but you don't want to be hemmed in by them, either. A lot of people never manage to find the right balance between being recognizable and vibrant that allows them to build a long and varied career. However, animator Don Hertzfedlt has definitely found a way to thread the needle.
Hertzfedlt's early animations had a style which seemed simplistic at first glance: his characters had stick arms and legs attached to bulbous oval bodies. While some artists use stick figures because it's what they know how to draw (XKCD I'm looking at you), I never got that impression from Hertzfeldt. He clearly had a lot of visual talent, but he wanted to do everything himself, and since animation is such back breaking labor, that meant that he had to simplify his style or go insane.
What he managed to do with that limited style was still amazing. His early shorts definitely had a crudeness about them, but his blobby figures were still very expressive, and Hertzfeldt could make you feel pathos for them. His 2000 film "Rejected" is a perfect blend of amateur and expert filmmaking, since it starts with his childish figures in silly situations, but as the film progresses, the world around those childish figures grows more complex and their problems become darker and more threatening.
Hertzfedlt could have evolved his style in a lot of different ways. He didn't decide to make his figures look more polished, nor did he abandon the silly humor of his early films. No, his later works still have some childish aspects to them - but they're longer, more complex, and increasingly existential. His 2012 film It's Such a Beautiful Day looks a lot like Rejected - but it's a very different beast.
The first obvious sign that It's Such a Beautiful Day is more ambitious than Hertfeldt's early work is it's length: while his first works were around five to ten minutes long, It's Such a Beautiful Day is just over an hour long. Narratively speaking, it doesn't quite feel like a movie, nor is it several shorts jammed together - it is an idiosyncratic story, told with confidence by a man who isn't afraid to head into the wilderness without a road map.
It's Such a Beautiful Day focuses on a mentally ill man named Bill. As Bill weaves in and out of coherence the movie weaves in and out of coherence. Sometimes the film focuses on the mundane details Bill uses to ground himself in reality, but other times it becomes strikingly absurd. Sometimes Bill's mother, his uncle and his ex-girlfriend appear, but then again, so does a strange figure with a fish growing out of his face. It's a singularly odd approach to depicting madness, one which bounces back and forth between first person and third person perspective. Ultimately, it creates a story that could probably only be told in animation, and which required a master animator to tell it.
While the narrative flourishes will impress people who know his early work, Hertzfeld'ts increased artistic proficiency will be obvious to anyone who watches It's Such a Beautiful Day. Bill is still a stick figure but his environments can be staggeringly complex. There are times when there are four or five windows open at once, all of them offering different portraits of what's happening in Bill's life. More importantly, there are a lot of textures built into the background, many of them superimposed from other mediums - sometimes Bill's mind is overtaken by actual fog, or he's confronted with real flame. Several times figures and photographs begin to blur together, suggesting that Bill and his family live in the real world, but he's only capable of seeing himself as a stick figure. It's a winning approach - it doesn't sacrifice the charming amateurness of his early work, but it adds a lot of visual complexity to the tableau. I have no idea how much work it took Hertzfeldt to create an entirely animated movie using such mixed media by himself and I don't want to know.
If Hertzfeldt had continued in his signature style - whether that meant making more shorts, or sticking to a simplified visual approach - I would have still loved his work, because we share an absurd sense of humor. But Hertzfeldt took what made those early shorts so satisfying and grew them into an engaging and mature masterwork. I have no idea what Hertfeldt will do next, but if his past work is any guide, I bet it will involve stick figures and I bet it will be mind blowing.