Many Restoration shamans donate for http://www.wowhead.com/item=54588 because of Haste. I understand it, it's Nice stat, but I already have 38% haste without Buffs, but still "too much water will not hurt". On the other hand they make a couple of damage Spells such as Flame Shock and Lava Burst and a couple of Lightning Bolts and get +1000 SP .. It's nice!
yes some people use it in combination with the flameshock haste relic (=overall: 400 haste + chance to procc spellpower)
But it's totally not worth spending so many global cooldowns on it, the haste improvement is not huge enough to compensate even one global cooldown that has to be wasted for flameshock.
but I already have 38% haste without Buffs, but still "too much water will not hurt".
The only stat you should go for is haste since it makes chainheal faster (and chain heal is the only spell you should heal with as long as you are not moving)
Haste improves your healing done by the most. Offstat should be crit + spellpower