elemental is a decent spec, but it got nerfed pretty hard in the overall dps aspect in 2.3. The upside is it uses a lot less mana than it used to, but they nerfed lightning bolt and chain lightning when they changed the lightning mastery talent, and the base cast time of each spell. Reducing the cast time on lightning bolt/CL basically reduced the effect of spell damage, and by a pretty significant amount, while 5/5 lightning mastery is still pretty much a necessity for an elemental shaman.
If that all sounds confusing... elemental shaman pre-2.3: 2 second cast time on lightning bolt, 1.5 on chain lightning, lightning bolt dps was very significant but it used up more mana.
post-2.3: 2 second cast time on lightning bolt, 1.5 on chain lightning, less damage but it uses a little less mana.
the overall effect is a big nerf to lightning bolt dps. it sucks, because I wanted to go elemental at 70, too, but it seems like it's just not as good now as it used to be, and for no good reason really. But because it was such a nonsensical nerf, they're going to have to do something to buff elemental dps in the future (possibly giving it a 41 point talent that's actually beneficial) so it may be fixed by the time you're 70.