After seeing the film I thought I'd read the script on line - Smith scripts are often entertaining to read because he's such a good writer and are often dialogue heavy. There are some interesting differences from the final film - the script is even shorter, lacking several moments back in the real world involving Wallace, and a scene between Guy and Howard. Wallace is more of a dick head in the script, going off to have sex with swingers (he tells his girlfriend, who is far less sympathetic here - she still cheats on him), more obnoxious. It doesn't have the convenience store girls and there's a different Canadian customs official.
The stuff involving the walrus transformation feels the same - and overlong, though the imagery and weirdness of it is there. In some ways I preferred the script's depiction of Wallace as a nastier person, it made his torture a little easier. It still lacks a strong third act, and feels padded even at this tighter length.