With the most recent alpha patch notes, HotW is now significantly underpreforming compared to NV and DoC for all 3 specs.
First all, this is not a complaining about T90 talents. This talent tier functions as a raid-healing throughput tier- NV provides a small but lengthy HPS boost on a short CD for a small period of time for all 4 specs, DoC, for non-restos, allows for better spot-healing through more powerful, instant healing touches, and for resto, allows them to attonement heal, contributing both a small amount of dps and healing. HotW does something similar, except also allows the druid to become an emergency tank for non-guardians.
As it stands, however, HotW will be rarely used next expansion - the only time that it would be worth being used is A) you need a temporary off tank on any fight, B) Resto wants to spend a long amount of time doing high damage/low healing, and C) Feral needs to range a mob out of reach, aka Atramedes. With the removal of many cat-form abilities, HotW will never be used to cat-form dps, and with the removal of Tranq from non-Resto, HotW will never be used to heal.
Now, HotW still provides a 25% healing boost in addition to non-resto healing boosts. However, DoC provides a 20% power boost to Rejuve and HT for Ferals, and causes heals by these 2 abilities to also heal the feral (Thus, the feral can toss out rejuves and insta-healing touches during empty globals that heal both the feral and an ally for a good amount), thus DoC trumps HotW for overall healing boost. For burst-healing, NV is significantly more powerful then HotW, as it allows 16% of dps to be converted into HPS for 30 seconds on a 90 second CD (33% uptime). Thus, HotW is a poorer healing choice for Ferals.
Boomkins, HotW requires a substantial period of time of doing low dps in order to get maximum benefits from the healing capability. DoC, however, gives you more starsurge/starfall usage in exchange for a single global, and NV is, of course, passive healing that requires only a single button push. HotW is again the poorer choice for healing.
For resto, HotW is a 25% extra healing CD for 45 seconds on a 360 second cooldown, for an overall boost of 3.125% healing. But wait! NV is a 16% healing CD for 30 seconds on a 90 second CD, for an overall boost of 5.28 healing! And its less prone to overhealing then HotW is! NV is the default healing choice here.
Guardians? They have to leave form to cast any healing spells. HotW is useless here.
Now, my suggestion is to make HotW a combo active/passive ability, with the affects varying per specs. The active affect has a 3 min CD, 20 second duration.
Feral- Wrath damage is increased 50% and has no mana cost. Rejuvenation and Healing Touch heals for 50% more. Healing Touch can be hard-casted in Cat Form. Can be activated, giving the current Bear buffs, and a 50% healing boost.
Balance- Sunfire/Moonfire tics heal a nearby friendly target for 10% of the damage done. Rejuvenation and Healing Touch heals for 50% more. Same activation as Feral.
Resto- Wrath damage is increased 50% and has no mana cost. Moonfire deals 100% more periodic damage and has a chance to make the next Wrath instant. Can be activated for a 30% healing boost, and current bear bonus.
Guardian- All damage done heals a friendly target for 10% of damage done. Healing Touch is castable in Bear Form, and generates 8 rage. Fairie Fire deals 250% more damage against targets 10 yds or farther away, and has no cooldown. Activation causes Healing Touch to heal ALL friendly targets for 10% of the amount, generate 12 rage instead of 8, and deal 100% of healing as damage.