Group play in Age of Conan is an interesting experience. In many ways it is very different than WoW, even though they are both games based on the trinity of tank-healer-dps.
The nature of AoC groups stems from how healing in AoC is designed. All three healer classes have the same type of spells. There are three healing spells: green, blue, and yellow.1 The green spell is a group HoT. The blue spell is a stronger HoT that affects people in a cone in front of you. The yellow spell is a direct group AoE spell, but a player can only be affected by a yellow spell once a minute.
So healing is essentially HoT-based. You put up your green and blue HoTs and then do damage until you need to refresh them.
The first consequence of this design is that one healer can heal multiple tanks just as easily as one tank, so long as the tanks are positioned correctly.
The next element in AoC group play is that mobs hit like trucks. The standard pull in AoC (so far) is two mobs. Each tank grabs a mob and tanks them next to each other. If you get more than two, the tanks try and hold them and the group uses knockdowns as much as possible. When a mob is knocked down, it doesn't do damage while it gets back up, giving the HoTs time to tick.
In WoW, this is the sort of situation in which crowd control would be used. But AoC is a PvP game, so all crowd control is short duration, on the order of a few seconds. As well, you don't deal damage to targets exactly, you deal damage to the area in front of your character. This means that there is a lot of splash damage, which would mean that crowd control would need to ignore damage.
With two tanks, boss mobs are often handled by the tanks swapping aggro. Since both of them are getting healed at the same time, one tank's health is dropping, while the other tank goes back to full. Of course, tanks don't have a threat meter or even a baseline taunt, so this can be pretty hard. A tank swap is often accomplished when the lead tank dies.
The long and short of this is that in AoC the normal group size is 6 people, and consists of 2 tanks, 2 dps, and 2 healers. Yes, that's a worse tank/healer/dps ratio than WoW. This is despite the fact that there are 3 tank classes, 3 healing classes and 6 dps classes.
Oddly enough, even though healing in AoC is fairly easy2 and tanking rather difficult, it's not that hard to find tanks. It's still hard to find healers. I think that's an interesting difference between WoW and AoC. Healers are scarce in both games, but tanks are more common in AoC than WoW.
Of course, maybe part of the reason is because I am starting late, and everyone else who rolled a DPS character rolled a tank to get into groups.
All in all, group play in AoC is different enough from WoW to be interesting, yet similar enough to be easily understandable. Now, if only forming a group didn't take several hours.
1. The spells put a colored circle around the feet of your teammates, so you can see who is affected by each spell.
2. At least healing is easy in theory. I seem to have a hard time finding healers who understand the idea of keeping the two HoTs up at all times.