The problem with open world RPGs is the monsters. Balancing the appearance of low and high level monsters is a bit of an art form -- if the monster levels are static, some parts of the map are inaccessible to lower level character. But if they scale totally, players don't feel progress. One of my (few) complaints with Oblivion was the scaling monsters. As your character got stronger, the monsters did too, leading to players never really feeling like they'd progressed. This is a problem that has apparently been addressed in The Elder Scrolls 5: Skyrim.
This, to me, is the best choice for the game. Fallout 3's progression of enemies was good. Maybe not great -- pick the right stats and find the right weapons, and you're close to invincible after a while in Fallout 3. But this is definitely a step in the correct direction for Skyrim.
Another lesson Howard learned from Fallout: The conversation system.
“There’s very few completely random conversations,” Howard said. “We’ve gone more towards a system, like we did in Fallout 3, where they have a specific conversation with a specific person about various topics.”
What do you think? Scaling monsters or static monsters?