Skyrim isn't a new IP. It's a game in the elder scrolls franchise, elder scrolls being the IP.
Obsidian is the core group of people responsible for fallout 2 and new Vegas, aswell as Baldurs Gate. They're a far more competent and creative development team.
Bethesda is using a modified 20 year old game engine, which is part of the reason their massive RPG's are usually kind of broken at launch. Their saving grace is the community that has learned how to use their dev tools over the last 20 years to fix, improve, and create new content for their games.
Bethesda creates phenomenal worlds with shallow mechanics in the post Daggerfall/morrowind era. Vanilla skyrim being the best example. There's no incentive to be the greatest wizard, warrior, archer, or rogue because you can do literally everything, no matter what your characters background is, because the role your playing is simplified to "protagonist" and little else. It succeeds in being fun in spite of being an RPG, not because of it.
Sorry for the rant, I love Fallout 3 and I can't stand what's become of Bethesda.