It was still a ton of fun to reappear in front of a large AI group, quickly disappear, then flank them while they all ran to where they last saw you and slowly pick them off. Stupid, unrealistic, whatever, it was enormously satisfying.
Not for me. Stupid AI in a stealth game is never satisfying. Part of the fun in stealth games is testing the limits of the AI. If those limits are immediately obvious, there's not much testing to be done. Using the cloak in Crysis completely removed all challenge because it broke the AI. Every situation boiled down to cloaking, standing still until you could get a clear headshot, turning off the cloak right before you fire, firing, turning the cloak back on, rinse and repeat until all the retarded enemies are dead.
I wasn't a big fan of the cloaking in DX:HR either but at least there, the cloak drained your energy really quickly and you actually needed to use items to replenish it.