I am at a Level 47 now, and pretty much can take down some serious badasses with just one shot. However, even when I was much lower level, I found that I could get through most dungeons/quests sometimes COMPLETELY unscathed.
I am a Thief/Assassin/Sneak imperial. Once you have a good bow and decent arrows, and have the good perks in Archery (especially the damage and the slow-down zoom), I found that you can stay in sneak mode, and snipe away at enemies without being attacked yourself. What I would do would be to use the Dragon shout "Aura Whisper" to find the enemies. Then, while in sneak mode, hit them from a distance. Then, all I had to do was move around a corner, or hide behind a wall (whatever). If the target wasn't killed immediately, then they would only make a desultory attempt at looking for you. You can even see their movement on your radar. As long as you have retreated and moved around a few corners or cavern bends, they NEVER come after you. Once you kill the first enemy, you SAVE, rinse and repeat until you have cleared the dungeon. I would do this consistently without even once being attacked. Of course, the Thief / Dark Brotherhood Assassin armor is important (as well as having good Sneak skills).
Besides the ease of taking out most any enemy (even when I was at low level), I still think the game is a blast. It is even fun to strategize where I am going to snipe my target from. Or, I change my mind, slip on my 2 x damage one handed Dark Brotherhood gloves and cut their throat from behind.
Good times