Back in Northrend

Well I got my warrior to 68 last night and got started in the Tundra, and I have to admit is nice to be able to take the quest upgrades than just selling the highest value reward every time. I seem to be running along at the same clip I was in outland but my friend who did the same with his rogue seems to think that the Northrend mobs are quite a bit tougher than the outland ones he had been fighting. So now I wonder is it just cause I'm a prot warrior or maybe that rogues are struggling in Northrend period or is he just exaggerating.