In my mind, orange mobs are hard. Like, your attacks barely dent them, while they crush you all the time. I'm currently repainting that picture.
While leveling through Northrend with Tirvin (my second pally past 70, by the way), I'm just having such an easy time it's getting silly. At level 71, I soloed Sarathstra for the quest Sarathstra, Scourge of the North. It was a level 75 elite, originally intended for a 5-man group. I was never even remotely in any danger, and killed her without using a single cooldown. The self-healing from Word of Glory kept me up with no trouble at all. In fact, I only spent about every second Holy Power dump on Word of Glory, the others went into Shield of the Righteous.
I did less dps than I could do with yellow mobs. However, my damage was much less reduced compared to what I remember from pre-4.0. Part of that may be because I had a decent amount of Vengeance all the time, but I didn't notice a lot of glancing hits. Similarly, I took much less crushing blows than I used to.
I tested it with other higher-level mobs too, and nope, they weren't really dangerous at all. At 72, I pulled groups of four lvl 75 mobs at a time in Grizzly Hills. With that many mobs, I was starting to take about as much damage as I could self-heal without cooldowns. If it weren't for the level requirement to pick up quests, I'd be in far higher-level areas already.
I'm also taking this opportunity to do some other quests I've skipped with my 5 other 80s. With all of those, I focused on quests that would get me reputation with the Northrend fractions. This time, I don't need to bother with that. In a month and a half, the reputation in Northrend will have very little to say, unless you're an achievement collector.
I'm looking forward to a lot of cool quest chains in Grizzly Hills. Just dinged 73 last night when I finished Battle for the Undercity. It's rather cool, and since it'll be gone in 4.0.3, I took the opportunity to do it one final time. Sylvanas and Thrall are just badass!
I'm looking forward to see how badass Baine Bloodhoof will be in Cataclysm.