How often she dies depends on how you play her.
I use her as a combined mage/healer and off-tank in a party with a MC Rogue, Lae'zel fighter, and Gale wizard. My Rogue and Lae'zel are always up front taking aggro and controlling the initial fight. Shadowheart starts as a back-line mage just behind those two, throwing buffs and debuffs. Her Charm spell lands often if you pick the right target.. Then I move her in for melee as needed for an off-tank.
If you rush right in with her as part of the main melee line, she doesn't do well.
