At present, the "Eternal Flame" ability is a talent in the level 45 "healing" tier for the paladin class in the MoP Beta, it is a holy power-based 30 second HoT with a single target restriction. It won't be a surprise to you that I'm bringing up this talent because I have problems with it, since I'm certain it's quite rare for people to open a discussion on this particular subject simply to offer praise.
As a talent, Holy and Prot players might consider this talent, but primarily for mathematical reasons over anything else. Questions start to come to mind when considering it, questions like "How is it affected by haste, and do the ticks crit?" or "How often [am I]/[is my target] in a damaged state for this to not be wasted on overhealing?", and it's not really a mechanically compelling ability; it's a HoT, that's about it.
One of the problems is that this talent can easily become your only choice if it's broken down to simply do better numbers. Heck, it'd be unambiguously mandatory for holy if it weren't for the target limit (Thank the light for that).
But the real kicker here is that I simply cannot see Retribution using this talent, ever. Not in pvp, definitely not in raiding. Retribution paladins already have to maintain a holy-power based buff through inquisition, and at least that increases your damage, Eternal Flame does no such thing.
Worse yet, the other choices are simply better. Sacred shield, while not absorbing as much as Eternal Flame heals, only costs mana, and it also buffs your FoL crit chance by quite an amount. Even in the middle of nowhere getting bared down on by another melee class, with the new Devotion Aura it isn't far-fetched to have a ret paladin spam flash of light in a pinch to get themselves back up, so that crit means a lot. Selfless Healer is entirely passive and even if you never use it on anyone other than yourself it's still fairly useful in a pinch.
And if a ret paladin needs to burn holy power to heal their self there's still WoG, there's even a glyph for it which (Albeit only slightly) mitigates the damage loss, for which Eternal Flame has no such thing.
So really, I just don't see the appeal of this talent, unless of course I'm missing something here.