Are you tutsi kidding me?
Playing a dual-wielding, heavy armored orc warrior on master difficulty. The game was difficult when I was level 15. Like really difficult at some points. Then I power-leveled smithing and made a full set of Daedric armor and two weapons.
Now I feel ridiculously over-powered, even though I gained a ton of levels.
Edit: Oh, and I have not even enchanted my gear yet, although my enchanting skill is at 65, adding quite a few more levels. I even have six perks yet to spend.