Since the talent applies to both melee attacks and spells, it is highly useful for both Elemental and Restoration specs. As it provides a solid bonus to critical strike chance and is a prerequisite for Flurry, Thundering Strikes is a staple talent for all Enhancement builds.
Thundering Strikes is in every way superior to the Tidal Mastery talent in Restoration, since it is not limited in what it applies to. The two talents stack, however. Thundering Strikes also stacks with the bonus spell crit chance from Blessing of the Eternals. Combining all three talents provides a +14% bonus to spell crit chance.
A Restoration shaman with at least five points invested in the Enhancement tree should never spend points in Tidal Mastery in the restoration tree that can spent in Thundering Strikes, unless the points in Tidal Mastery are required to advance further into the tree. Even then, only the minimum number of points required to advance should be spent, with the remaining points placed in Thundering Strikes.