Pretty decent build.

First: Thank you very much for your comment and vote. :)
Good guides so much depend on the community.
To be honest I get Hextech Revolver first most of the time. But I find Rylai's Crystal Scepter is by far too powerful to be left out of any Akali build. The slow effect is incredible powerful.
I'm considering Sheen right now. I prefer other items most of the time, but Lich Bane can really shine late game, where you may have tons of AP.
Sheen on its own only doubles your AD. Which is but a quarter of Akali's damage from AP and in my opinion not worth the delaying of other more important items.

^

I think Hextech Revolver is a must for Akali, you can't sustain yourself effectively without it (It shouldn't be a situational item, Hextech Gunblade and Will of the Ancients are good items too).
Maybe something like boots+3pots->revolver->boots->sheen->guardian angel->lich bane->hextech gunblade->rabadon>void staff would be better purchase order.

Going to +1 because you've put a lot of effort, it's well written and have cool tips/tricks. :)

Reserved for future updates/news