The director's cut strips away the unnecessary narration, much like the superior cuts of Bladerunner. It does add some footage, but nothing of really grave importance--mostly just establishing shots and slightly extended scenes, if I recall correctly. There's nothing quite as impactful as the 'early' ending in Bladerunner, or the unicorn scene, but it's still a better experience than the theatrical version by some distance, in my opinion.
I suppose the film-noir style of it might throw some people off, but I find that it gives the film a special character that a lot of sci-fis lack. Its homages don't end there either--it also visually pays tribute to several silent film classics, as well as to Akira. Oh yes, and there is a very sneaky (maybe just flat-out unintentional) 2001 reference.