My guild had a shitty time on Norushen. It turned out to be a chink in our strategy. We were originally counting on each dps to signal the next to take a portal once their big add came up top, and we were always hitting enrage at sub 5%. Then we changed it last night to every 20 seconds another dps goes down. Got the kill with 14 secs left on enrage first try using that change. Man I wish we'd have thought of it sooner, we'd be on Juggernaut easily by now as we continued the raid on 10-man (We're a 25-man guild) over the weekend and got Galakras down and almost Juggernaut if we had more time.
On topic: Definitely fairly easy in the beginning especially on 10, less on 25, but starts to climb difficulty sooner than you'd think.