GNB is the 3rd place in terms of mitigation when comparing to other tanks, but thats by no means bad. Camo being an extra CD, with the parry element is nice especially on packs where most damage is physical, aurora is as strong as an equilibrium/unbuffed clem only over time, and an argument can be made for HoS being stronger than shelltron despite having less % mit due to the nuances of how shelltron works (nullifying passive block, overwritten by crits, doesnt stack with parry, not immediately available)

Overall whilst you're not almost immortal like WAR, or very beefy like drk with TBN, youre by no means squishy, and ironically have better mitigation than the tank with the shield.