Invisibility potions, Refreshing Path or the Shade morph that lets you teleport back to your shade? Also cripple them before you run away.

Roll dodge 2 or 3 times till you are done being hit by projectiles, pop dark cloak, change direction, get behind a rock or tree...etc.

Need max sneak speed from Night's Silence or Vamp though....or a ton of magicka to constantly recast dark cloak as a slug away.

Dark Cloak is still the method of choice. As a few have stated, it helps to roll once or twice and dodge any range attack already cast at you- that is what will pull you out of your cloaking. Dark Cloak isn't as broken as most claim, it is just not a fool-proof method of turning invisible. If there was something cast on you right as you cloak, or sometimes if you're snared, it will pull you out of the cloak spell, which is unfortunate.

Keep working on it. You'll find the timing, which is 80% of using the spell. Stamina-based NBs will have more difficulty using the skill because they tend to lack the magicka it takes to cast it continuously, and also tend to lack the speed while stealth (having Concealed Weapon slotted as a magicka-based NB gives that extra speed necessary to escape).

But keep in mind that Dark Cloak is just as much an offensive ability as it is defensive. The skill is still very much an important part of most NB builds, often slotting it on both bars. It can be sensitive to some users, you'll just have to find that moment when you know it will work in to your advantage.