Shaman are hybrid by nature. But usually for all classes, specializing in one or two things makes you more powerful. Shaman can be secondary healers, but if you want to heal, make a priest.
But in PvP, using spells as a shaman is very very powerful.
I was going to go about 65% enhancement 35% restoration (to get nature's swiftness.)
Some people go like 70% elemental and 30% whatever else. It just depends on what you want to do.
Overall, melee is easier and has less downtime because it isn't mana dependent.