It's really one of those many items that either of the intended classes can use. But as a rule of thumb, generally tanks and healers get first pick due to there being not as many options for them and harder to get anything on their own.

I personally wouldn't let a Holy Pally (I have one), Enhancement (and one of these) or Resto Shaman roll on this if there was a Prot Pally or a Elemental Shaman who needed it.

Basically the crit is more for a Elemental Shaman but the armour and block is for the Prot Pally though none of the stats are wasted on either.

If the pally had a warrior type shield (anything without int, mana regen or spell damage) and was hurting for caster stats then he/she would get preference.

Other than that words of advice, be nice to your tanks and healers otherwise they may tell you to roll one yourself as they exit the guild (this doesn't mean you have to bend over backwards for them). ^^