The problem with Lightwell

I recently respecced my Priest and I decided to take Lightwell, even though common sense and the Priest community all said it's a shitty spell not worth the talent point.
Spell description (screenshot from wowhead):



Aside from the obvious technical difficulties - 6 min cooldown, damage taken cancels effect - I think this comment from wowhead sums up the main problem with this spell very well: "A heal that relies on the competence of other players to be efficient and effective is an interesting idea but it rarely works out."
This has also been my experience. Even in situations where I saw Lightwell could be useful, the spell's healing relied on the other people actually using the Well. If they forgot/were too busy, the spell had ZERO usefulness to them. Even if they did use it, if they forgot to stay away from damage, the quickly lost the effect - this happened more than once.

I see a quick respec in my near future... ;p