I don't like having fights all scale to your level automatically. I'd rather they be designed at fixed difficulty and range from trivially easy to virtually impossible (with most somewhere in the middle), depending on what level you are when you get to them. Paired with that, the game needs to give you some means (through skill checks) to assess your strength against that of an enemy and perhaps ways to find/recall weaknesses in the case of very powerful enemies.
If every fight is scaled to your level, then you go into it knowing that it should be about as difficult as every other fight you've been in and you should be able to win it about as easily. It doesn't feel like there's any risk. It misses out on the feeling of triumph that comes from eking out a victory in a battle where you were outmatched, but well-prepared.
I mean I don't mind the game being designed around either way honestly, but I have played games that have dynamically managed the level range, and NO, that does by no means guarantee a victory. Just because you are all the same level, does not take into account elites, or other more powerful version of combatants that are still at your level, but could kick you ass. A perfect example is the spider cave battle with the patriarch, which honestly, I though was one of the most challenging fights in the game. They were the same level, and that fight could wipe out your party in any round if it got the right rolls.
