I have 4 x Hunters + Druid at level 80. I will just confirm what was already said :

- Levelling is great, easy and fun, both outdoors and in instances (with AOE pets like gorillas). I did levelling with 4 beast mastery hunters and a resto druid.

- Heroics are simply not possible. Even trash mobs chew through pets in no time. I tried again after gearing my hunters in early epic PVP gear : same result.

- Battlegrounds are great fun. I respecced hunters to mark and the druid to range DPS, though. I found that to be more efficient. The team can really make a difference in some cases, quite impressive.

- Arenas are a no go. Admittedly, I am probably just not good at arena at all, but I never won a match. Ranking 0, after more than 100 matches. Not fun at all, I did it just for the arena points to buy starters gear faster. Well, not fun, but rather laughable to see how quick some mêlée teams could go through my hunters.