shamies grow in power exponentialy as they grow in levels.

i had so much trouble getting hrough level 27-29 (i only MB 3 shamies) but suddenly i got 30, Windfury and Elemental Fury and somehow it started to click together.
Now i just dinged 32 and here comes Chain Lightning! awesome. Can't wait to get to 40 for Elem Mastery and Chain heal. Then i'll just roll over my face on the keyboard for xp :-)

if you're 30, go do a couple SM graveyard, or RFK to get a level (i got half a level doing RFK -everything except the trench, cant be bothered, and about the same in SM GY) just 3-maning it.

I'd say keep to it and try for level 40 before you make your decision. If at 40 you still dont enjoy it, then yeah maybe it's not for you.
In any case, that's the line i'm following. I always haev my toons (even solo) up to 40 at least and then stop or continue.