The Sperm Whale has a very interesting outline, and yes it kind of does look like a sperm whale. Wide nose and middle, with a narrower tail.
Check out Dane Reynolds, the designer himself, getting rad on his Sperm Whale:
Very flat deck might make it hard to get the board on rail for turns. Combine that with the extreme width of the board, and you can see that you won’t be doing lots of turns with it. (You might think otherwise, after watching the video above, but remember how good of a surfer Dane is). However, there is a good amount of V in the bottom of the board, to help compensate for the width.
There is some tail rocker to make it more forgiving when surfing in pockety waves, instead of just laid back mushy stuff. However, it’s best meant for easily gliding and trimming.