Got to sample a portion of the formidable U.B. Iwerks' works, particularly his Flip the Frog and Willie Whopper cartoons. The classic complaint is that Iwerks couldn't create an interesting character, or an engaging story; true to some extent, I suppose, but after watching one Flip the Frog after another, there's something appealingly, well, flip about the frog in his opening credit sequence, the way he would tinkle the keys, then look over his shoulder and burp at the audience (I think if Iwerks could have somehow transferred this mysteriously reassuring presence into the actual cartoon, he might have had something).
(I might note by way of defense that I don't remember Mickey Mouse having much of a personality, either; he was mostly the hero type (but then, so was Flip), and as the years went by and Mickey's status rose and he became the symbol of the entire Disney megaconglomerate, so many restrictions were put on his character that he became impossible to characterize (he couldn't do anything, much less do anything entertaining). All the mischief and fun drained off to the supporting characters, like Goofy and (best of all, in my opinion) Donald Duck.)
Actually, the real star of Iwerks' shorts is the animation and Iwerks' rather unique sense of humor (Chuck Jones, who once worked for Iwerks, says Iwerks is "screwy" spelled backwards). Iwerks goes for the visual gag, often surreal, often sadistic and cruel; unlike Disney, he's not averse to populating his shorts with girls--real girls, not sexless boys in drag, with breasts and buttocks and long, shapely legs, who are either wearing diaphanous negligees or are caught in their underwear, trying to put something on (or take something off). His Room Runners (1932) would seem uncomfortably voyeuristic, with Flip and various hotel staff peeking through keyholes at half-naked guests, if it wasn't so irrepressibly funny.
He's also not averse to the rather grim ending (grim, that is, if the gags weren't so funny): in What a Life (1932), one of Flip's more memorable adventures, Flip struggles at the simple task of surviving, and unlike in most Disney shorts, he doesn't miraculously find fame and fortune; the struggle continues.
Spooks (1931) is mainly remembered as Iwerks' Flip the Frog remake of his classic The Skeleton Dance (1929) with Disney, and for suffering from the comparison. It does, pretty much, but Spooks does have a plot development far more gruesome than anything in Skeleton Dance, when the host takes out his knives and decides that Flip would make a nice addition to his menagerie of bony animals (which includes a delightful skeleton flea, feeding off of a skeleton dog...).
Willie Whopper is possibly even less appealing than Flip (unlike Flip, he isn't blessed with a delightful opening number), but for some strange reason some of his adventures are quite memorable--The Air Race (1933) comes to mind, with an indignant pilot giving another the finger, and Whopper's propeller plane transformed into a rocket jet. Then there's the bizarre Stratos Fear (1933), where Whopper inhales a huge dose of laughing gas and hallucinates floating into outer space and landing on another planet: there he encounters a mad scientist who invents a ray that twists and turns around corners, and reduces objects to their end products (a cow hit by the ray becomes beef, milk, and cheese). Windows zip up, entrances narrow and slide away, a woman in a see-through dress lures Whopper into a room where she transforms into the ogrelike scientist. Iwerks might be drawing from personal experience here.
Easily the strangest of Iwerks' strange works is Hell's Fire (a.k.a. Masquerade Holiday, 1934); Willie Whopper, in full color, falls down a volcano and finds himself in an inferno populated by Napoleon, Nero, Rasputin, Simon Legree, Antony and Cleopatra, among others. Cerebrus comes out of a dog house with three heads and a nasty temper, and--naturally, considering this is hell--finds himself infested with fleas; a man trying to escape hell is tormented by a giant fiery drill, digging its way into his behind. All done in the cheeriest tone of voice, to bright music and even brighter colors, but without the jokes and comic trappings, this could be the grimmest animated short I've ever seen.
Then there's Balloon Land (a.k.a. The Pincushion Man), about a land of balloon men, women and children menaced by a creature made of needles (as potent a metaphor for the fragility of human life as anything I can think of). Strange as the idea is, the execution is even stranger: a swift and cheerfully scored cartoon where this bizarre spikey villain massacres a good portion of the population. Couldn't tell if I should be amused or horrified, and I think that's the power of the cartoon.