There has been a lot of controversy over the design of the upcoming Legendary Rings in patch 3.2. Here is the current ability of the healing ring:
Use: Awakens the powers of Sanctus rings worn by you and your allies, granting (772/100)% Versatility for 15 sec.
For the duration of this effect, all damage and healing received is divided evenly among empowered allies. (2 min shared cooldown)As you can see, invoking your ring also triggers the rings of your fellow raid members. This is pretty controversial, because different classes might like to trigger their ring at different times. As well, it feels like you are giving up control of your Legendary item to someone else, be it the raid leader or just another player. Players really do not like to give up control.
The major issue with this ring though, is something slightly different: The cooldown is too short.
This ability is clearly modelled after Bloodlust. Bloodlust (and its variants) is an iconic raid-wide ability. It has a very noticeable sound and graphic, and is a very important part of raiding. But Bloodlust also has a 10-minute cooldown. This means it's only used once a fight (maybe twice on the very long fights). Thus there is some coordination, saving it for a specific phase. But at the same time, that coordination is limited. You just says "Lust at the start of Phase 3", or whenever it is necessary.
A two minute cooldown ability, on the other hand, needs to be used as much as possible. Ideally it should be used whenever it comes off cooldown, to maximize the uptime. That means lots of coordination to get the timing right. As well, if the ability is triggered incorrectly once, it throws of the entire schedule.
If I was designing the Legendary ring for a raid-wide effect, I would do something like:
Use: Increases haste by 30% for all party and raid members within 100 yards. Lasts 40 sec.
For the duration of this and similar effects, you gain Legendary Heroism, granting (772/100)% Versatility. All damage and healing received is divided evenly among allies empowered with Legendary Heroism.
Allies receiving this effect will be unable to benefit from similar effects again for 10 min.Basically, this ability is "Improved Bloodlust". You get the ability to invoke Bloodlust if you don't have it already. But now you become even more powerful under the effects of Bloodlust.
This allows Bloodlust to do the heavy lifting in terms of how the ability works in the raid. Everyone already understands how Bloodlust works, and how it should be coordinated. It really only activates once a fight, but it activates during the most important part of the fight, usually the most dangerous phase.
I think a design like this is just as "Legendary" as the current design. But it utilizes existing mechanics, making it easier to understand and coordinate.