The Alchemy is for the gold, more than anything else.

Initially Truegold was the best transmute for gold profit.
It quickly switched to Volatile Life > Volatile Air.
For a little bit, Truegold was the top again, but Life > Air is currently the most profitable.
I've spent close to 400k this expansion, on: Vial of the Sands x5, 310% flying for everyone, starter crafted PvP gear for two teams, etc... and am still 350k ahead of where I was pre-Cata... and that is entirely alchemy transmutes.

Alchemy is probably not the best for pvp play.
You get the reusable Flask that is 80 to your highest stat (from Str, Agi or Int).
Not a bad bonus for PvP, but nothing special either.
You do have the freedom to buy things, such as Engineering or an epic weapon etc.