The first thing I would suggest is checking out a page or two of the forums and reading individual threads about the different specs: enh, ele, and resto. Generally, most people believe it's a shaman's strong suit to go resto for PVP purposes, followed by ele and then enh.
The problem with resto, IMO, is that while your survivability shoots through the roof with earth shield, your dps falls drastically. So, while you have the time to outlast "that rogue" in PVP, it's incredibly annoying because you're not doing much damage to him. In the same respect, the "resto" viability becomes more and more evident if you have people fighting with you.
Keep in mind, resto is not a solo build. So, if you do things on your own, I will venture to say that it will start becoming un-enjoyable in the very near future. This includes doing dailies for money, grinding rep, and going into BGs w/out a premade. I'm not trying to steer you away from it, just giving you something to think about.
Elemental is my current spec, and I enjoy PVPing. I'm definitely not covered in l33t elemental gear, and I still topped the AV damage charts earlier this week. (75% horde were AFK ... gg dps shaman ... lawl)
Problem with ele is that I am really squishy now. I am a target and I die more often, simple as that. I don't mind it, however, because I'll tell you what sucks: when you're out in the world as a resto shaman, and you come across a 70 whatever, and you have to avoid it because it sucks trying to gank someone. Seriously. Maybe I need to L2P Resto, but if you're worried about the drop in DPS, take it from me that you will definitely notice it.
Oh, and healing wasn't as fun as I thought.
GL.