My current spec is this. I don't have Lava Burst yet as I've effectively wasted about a level's worth of time leveling my alliance shaman then switching to horde and then getting the XP increase board in the face, but even without the crit synergy it's working out for me. There are a few mobs that root/snare making the combination of instant cast Ghost Wolf and Spectral Transformation worthwhile, although I wish it made my Spirit Wolves last a little longer. At 45 seconds, they're effectively an 'Oh crap' button for me now, but in that role (or in a burn down phase) they're very nice and immune to various unpleasant stuns, snares and roots that would keep them from doing damage.
Dropping totems for synergy (Strength of Earth, Healing Stream, Windfury and Searing are my current soloing totem choices) with Maelstrom Weapon has me convinced that enhancement is definitely going the route of an offensive caster hybrid. You won't itemize for spell power like elementals do, nor will you really bother with much spell crit once you have Lava Burst to synergize with Flame Shock (I still can't report on whether or not you're going to end up seeing all of your flame shocks used up by elemental shamans' Lava Bursts, though, it is definitely something I'm eager to discover as time goes on) - even without it, I'm finding the instant cast LB's and Chain Lightnings crit enough (since all +crit items add to both spell crit and melee crit) that I'm getting a great deal of benefit from elemental devastation. I hasten to point out that while actual crit rating on gear adds to both melee and spell crit, stat derived crit (say, from agility) only adds to one or the other. So my melee crit is still higher than my spell crit, it's just not totally lopsided.
I have been concerned with loss of hit through talents, which I felt to a degree in my runs in Utgarde and the Nexus. It's still kind of early to cry an alarm on that one, and I expect itemization will catch it up. The mail needs for enhancement shamans are almost identical to hunters now, with agility and intellect granting AP, so the hit heavy hunter mail should help patch that loss.
I'm positive I could have a much better spec for pure DPS in instances (I didn't take Improved Windfury Totem), and while I find the quest rewards adequate I do feel like I'm working very very hard to keep my cirt rate reasonable as I level. I'm really unhappy with the talent Static Shock which I tried out and then specced away from: it's really only good if you have Improved Shields, which I passed on to get down the tree faster in order to have room for my elemental talent choices. I'm debating going back to get it, though, if for no other reason than to increase my mana regeneration: mana is the biggest issue for me as far as soloing or questing is concerned. It's not terrible in instances, where other people need to stop and drink enough that I can keep up, but often if I get one or two adds during a quest, I come out absolutely empty of mana even with Shamanistic Rage.
To report on WF totem in instances: well, it's more popular with everyone but warriors, basically. Druid tanks love having me along for the combined strength and agility benefits of the new SoE totem in addition to WF's haste benefit for the melee. I can even drop WoA if the group happens to be caster heavy, although in my five mans to date it's not been the case. (I did the Nexus with three DK's and a paladin healer, and they liked WF's haste just fine, although I still don't know who the tank was on that run.)
Enhancement as a tree is at once very familiar (you hit things and throw shocks, it's a superb tree for grinding/leveling) and yet very different (getting the stacked Maelstrom to throw an instant, spell crits jacking up the melee crit rate) with a really definite hybrid feel. This week I'm going to see about burning my way to the level cap (it seems to take me about a week or so of solid play to make it with the new XP setup) so that I can give my full attention to elemental. Elemental definitely seems to be a work in progress right now, and I hope to have more detail on what I see working in that tree for next week's column.
The final verdict is, if you liked enhancement in TBC, you're going to like it in Wrath. It's been, well, enhanced.
Sorry, that was awful. Seriously, though, the talents seem to be meshing well, the gear seems to be stacking up to meet our needs, and in general there's a lot of promise in the spec. I'll report more on PvP viability once I can get into Wintergrasp, but for now I'd give enhancement a thumbs up.