Nah.. play a shaman and then say that. Their DPS is terrible in comparison. In groups, nobody wants you to play offense. They just want you to be a healer, and you don't get as much mana, so in the lower levels, by healing you use up the mana fucking fast.
Also, they're only decent in PvP. Most other classes can beat them if the players know what they're doing. Only way a Shaman can beat someone is if the other person just has -shitty- gear, and they don't know how to play their char.
I will say though, that Shamans are decent at soloing... to an extent. Still, they're mainly just a support class when it comes to grouping.
Mages are simply more -powerful- though. You need to play a Shaman and compare them.. I've played both, and Mages kick a Shaman's ass in PvP. Fucking frost = slows = shaman is fucked... not even totems can help that. Also, totems cost mana to put down, and some have a higher cool down. Totems are pretty useless in general right now though... I only drop maybe a strength totem if I'm going against something with a pet right now.
Still a fun class to play, but christ... even with about 360 armor right now, my friend's rogue drops shit in half the time it takes me, and ends up taking half as much damage