jungle akali is suuuuper strong now, esp with the buff to spirit of the specral wraith
20% cdr on smite, cheap spellvamp and +25% damage to creeps? gg
My Buying Order:
1. Machete + 5 Pots
2. Spirit Stone + Boots
3. Revolver
4. Spirit of The Spectral Wraith
5. Giants Belt + Merc's Treads
6. Rylais (usually by 15 min if you forgoe the mercs treads)
7. Gunblade
8. Any other high AP item
By the time you get gunblade you have >50 percent spellvamp, and retarded chasing power. Your clear times are pretty good due to having smite up all the time, and your ganks are unstoppable.

(only the first game on this list is jungle akali)
Why jungle akali over top lane akali? Because you get dunked pretty hard by most of the other melee solo tops (Darius, Jarvan etc) and at any rate they're too tanky (most of the time) to burst down with any ease. Mid akali is still a good choice (lots of squishies to feed on) but it's really fun to be able to roam as a jungler.
When to not pick akali: when the enemy has in excess of 2 tanky dps heroes and/or lee sin