Let's get durid.
Druids have three specs. Like all hybrids, the role of a druid depends greatly upon its spec. Unlike all hybrids, druids have basic tools for each role available at all times. This makes for an interesting class and I will detail the effectiveness of each spec in certain areas. Being an MMORPG with nearly five years under its belt, this is merely a guideline and your mileage may vary.BalanceFocus:
Balance really focuses on pumping up your ranged dps via spells. A mix of DoTs and direct damage, the Balance druid pumps out the dps.Leveling:
Balance has come a long way since launch. Once you get Moonkin Form, you'll be drinking less and putting the hurt on more. Nonetheless, caster itemization for 1-60 is quite...poor and even worse if you want leather armor. While improvements were made in 2.3, this requires quite a bit of instancing as quest gear (for the most part) is quite lacking.
As you enter Outland and Northrend, thinks look up. More modern itemization philosophies benefit you greatly and you have your full set of talents. Focus more on killing things with Starfire while reducing your need to drink. DoTs take too long to really do their stuff, so don't worry about those.PvE:
Balance has come a long way since launch. Moonkins are among the best AoE classes, which is quite relevant at the moment because trash in raids are easy to AoE down. They also bring multiple raid buffs such as 13% spell damage, 5% crit and spell haste. And then you have basic druid perks like Innervate and Rebirth. No longer an outcast, many Moonkins have found homes in raiding guilds.
Balance has also gone from CC-light to CC-heavy. Roots can be cast indoors and more targets are available for hibernate in Northrend. Throw in Cyclone and you can briefly CC three mobs.PvP:
Balance has come a long way since launch. Thanks to an improved Nature's Grace, machine-gunning Wrath is great burst and all the CC of a druid is contained in Balance. Throw you in some heals and you have a class that isn't top of the heap but still functions quite well in PvP.Feral CombatFocus:
Unlike most trees, Feral has two features: tanking and melee dps. As a result, several talents go off on their own path, meaning that you'll have to do decide if you want to perfect your tanking game or dps.Leveling:
Feral has been the leveling tree of choice for years now, and for good reason. Gearing up is easier than other melee classes because your weapon auto-levels from 1-60 and with we aren't picky about our weapon so long as the AP is good. No need to drink, multiple ways to escape in PvE and life is good for the feral druid.PvE:
People love tanks and, thanks Blizzard's new belief in four equal tank classes, bears will always be a welcomed addition to any raid or group. The same can't be said for cats, which are in need of buffs (coming in 3.1), but the dps is still good enough for the druid to help out when not needed for tanking. Druids brought exclusively for cat dps is still quite rare, as Moonkins are probably a preferred choice.PvP:
All druid specs are doing alright in PvP. We aren't a big name like Resto in seasons three and four, but you really can't say any spec is gimped. This is also true for feral, which is hard to CC and has ridiculous burst damage if allowed to stay in cat. When under pressure, a bear can hold out until things are clear. Shifting is dirt-cheap now, allowing for more heals and CC to be tossed around.
You can go far with feral.RestorationFocus:
Having evolved from the early days, Resto druids now have a strong identity with their Heal over Time (HoT) spells. Weaving life the way an Affliction Warlock weaves deaths, a Restoration druid focuses less on big numbers (but we can do, don't forget) but rather a constant stream of healing.
There's a bit of hate on Resto that dates back to the days when Balance and Feral were incredibly bad specs and people were violently opposed to any attempts for the druids to branch out into other group roles. Like most hybrid classes, telling a druid to heal may still ruffle some feathers and receive some growling.Leveling:
Being focused on restoring HP rather than depleting it, Resto pretty much sucks at leveling quickly. Some changes to itemization do help (such as the distinction between +healing and +spell damage being removed), but the Resto druid still lacks the refinement to his or her damaging moves that talents provide. Leveling as a Resto druid is a slow process. No way around it.
But, if you intend on doing instances with friends to level, Resto is pretty solid there. But only if the bulk of your time is spent in instances. Even if you split solo leveling and instancing 50/50, it's better to just go Balance and heal with that spec.PvE:
Healers are always in demand. Druids have a number of instant heals to save the tank and by providing HoTs they keep the tank's HP smoother by healing between the cast times of other, normal direct heals. One weakness of the druid, AoE healing, has been fixed with Wild Growth and improvements to tranquility. We even have a fast "Flash Heal".PvP:
While they can hold their own, Resto's days of dominance are in the Lifebloomed days of Seasons 3 and 4. Lagging behind Resto Shaman and Holy Paladins, druids can still succeed in arena, but it might be harder for you. But 3.1 holds a number of buffs for Resto, so perhaps the glory days will come again.