One of the main disadvantages is that a player is only resurrected with 25% health each time, so party members should be quickly healed if resurrected this way during battle. A more notable disadvantage is that targets are resurrected with 0 energy. This can be crippling for casters such as Elementalists, who can find themselves virtually useless while their energy recovers.
Because of these drawbacks, Resurrect is a poor choice for resurrecting allies in battle and should not always be your automatic choice if you have a monk secondary. In areas or missions where there are a reasonable number of morale boosts on offer, Resurrection Signet or Sunspear Rebirth Signet should be considered instead.