You may be wondering "how is this different than a normal playthough?". I don't powerlevel. I don't try to beat the game (or, since TES is nearly endless, try to reach a certain point). I just do whatever I feel is appropriate at the time. I guess this is essentially roleplaying, with me role playing a character just trying to get by in life, but it's slightly different since there are some limits placed by the game ( perks for example, since in real life there would be no limit to one's learning, wheras I believe there won't be enough perk points to get every perk. I could be wrong though since I haven't gotten that far into the game, though).
On the topic of perks... That's one problem with my style - I'll put some points into a perk tree, then realize I don't like that skill, and have wasted perks. this is frustrating, but it also adds to the difficulty a bit.
All in all, I'd recommend this for anyone who finds the game too easy. I'm 19 hours in and level 17. Blacksmithing and enchanting and whatnot aren't being insanely leveled considering I'm not buying/selling materials. I couldn't even if I want to since I'm saving up for a house (money surprisingly doesn't come easy when your primary source is loot, atleast while the enemies are weak). The absence of uber smithing and enchanting means my weapons come from what I take from corpses (I can enchant\smith roughly what I find on corpses my level, which is just the way I like it).
Overall I just feel like I am taking better advantage of the open world than people who know what the want beforehand, achieve it, then go and play the game afterwards. Admittedly, though, that is likely just me being biased.
Also, I am referring mostly to the console version, since on the pc you can change the game is virtually every way, so there is little reason to play this way (I figure the people who got the console version and the people who got the pc version had different ideas of what they want from the game.)