Druid Overview
General thoughts
The Druid has several play style options, you cannot be equally good at all of them. Let's look more indepth at your choices:
In normal (caster) form, a druid uses spells or weapons and is mostly specced in the Restoration tree, having Healing as their main focus. With its ability to heal itself and fellow characters along with a limited use resurrection, the Druid can also take on the role of a Priest. A Druid is not as versatile in its abilities as a Priest is, lacking the spell Holy Word: Shield and having slower, less powerful heals but is otherwise a very capable healer.
In Moonkin form, a druid is a high armour caster that can fight with spells or weapons. A Moonkin druid chooses to concentrate their talent points in the Balance tree. While not as powerful in dealing damage as a mage, we have the advantage of being able to wear leather armour along with the armour bonus from Moonkin form. Druids who concentrate in either of these lines should be on the look out for +INT items to maximize their mana pool.
In Bear form the Druid becomes a Warrior with Rage, while in Cat form the Druid becomes a Rogue with Energy and stealth. The Druid can also transform into two other special animal forms, one being aquatic (seal) form giving them the ability to breath underwater and swim quickly, the other being travel (cheetah) form, allowing them to run much faster than a humanoid normally can. The Druid's third talent tree is the Feral tree. Here you can maximize your potential as a shapeshifting druid. Feral spec druids should concentrate on maximizing their +AGI gear.