Jheherrin

Mental Dexterity - Increases your attack power by 100% of your intellect."

This is essentially a way of getting us to change focus on which gear we aim for.
The majority of Enhancement Shaman tend to find that leather melee gear, usually rogue gear, is better for dps, at the cost of armor and intellect.
This talent will make gear with intellect much more attractive. OK, we will still share leather gear, but the druid gear will be more attractive than pure rogue gear, and the mail gear that is supposed to be our class gear will also become more appealing.

It also reduces the need for us to choose mana increasing, or mana cost reducing talents by encouraging us to use gear that will increase our mana pool.

Mental Dexterity combined with the changes to hit and crit, make Totemic Mastery the only justifiable reason to subspec resto now. Elemental subspec with Concussion+Elemental Deavastation look far more interesting.

The main question will become this. Does my increased mana pool from gear offset the extra cost of dropping totems from loss of Totemic Focus and Totemic Mastery?