Aside from the usual technical excellence of Alan Moore and Brian Bolland's work in their primes, I'm not much of a Killing Joke fan for its darkening ramifications on the wider DCU (though Barbara Gordon as Oracle is the ultimate sow's ear-to-silk purse story in all of comics, thanks to Ostrander/Yale). The original Killing Joke film adaptation written by Brian Azzarello (a good enough writer but undoubtedly a poor man's Garth Ennis who is himself a poor man's Alan Moore) was a bloated, character-betraying mess and the animation was utterly banal DC DTV house style. (For a better visual adaptation of TKJ, I implore all to check out the Zellers Batman commercials by veteran animator John Celestri.)
BlueYoda has done the best possible job of reining in the bloat of the original cut, allowing what is now a faithful adaptation of this undeniably important comic, and it is exciting and even revelatory to see some of Alan Moore's subtler scene shifts (a trademark of this era) take place. I have to admit, a few of them (the cut into Jim Gordon's apartment for example) had never occurred to me.
So a much-improved version of a mediocre adaptation of a seminal but depressive comic. Hard to say I'll revisit it but for the curious, this is definitely the version you want.