I don't like WW much either, I guess I feel I should be doing something more important like waiting to interrupt vital skills, or shutting down. Than using my energy for 'possible' damage.
WW is a good skill though, just not one I like to use much

I don't like using Backfire either, however it owns in Challenge Missions.
I tried Mes/Ele with Glyph of Energy and Gale/Blinding Flash, with some inspiration/interrupts. Harldy any damage but it could really shutdown stuff in PvE, blind a taget, knockdown a monk/caster, blind another melee, interrupt, blah blah. While your team has an easier time taking em out.
Great overall skills for PvE are: Clumsiness, Ineptitude, Images of Remorse, Cry of Frustration, Guilt & Shame, Power Drain, Drain enchantment, etc.
Oh Arcane Echo is another skill I dislike. Requires too much energy, and its easy to overlook a build that uses it to get rid of arcane echo and put something else in that in the end is more effecient. Really just good for do or die elite skill skill builds.
I think mesmers probably have to shift targets more than any other class to make full use of their skills. On a final note, has anyone found Psychic Instability yet?
