A reasonably useful talent for a Main Tank type of role, as Sunder Armor is one of the three key abilities the Tank will be using over and over. However, as a Main Tank in group work, rage generation tends to be very high anyway, so 'savings' type talents aren't as important as in solo work.
Its position on row four of the tree means that it is likely to be impractical for any warriors who aren't planing a significant Protection build (i.e. Arms/Fury MS Soloing builds), making this mostly one of for post-60 Raid Warriors.