It is quite the different experience than Oblivion. Combat wise, it is much more tactical, allowing you to pause and give out commands, or do it in real-time. The plot, as far as I know about either while might be superficially similar, they differ (the whole evil invasion thing). Oh, and the characters? You just can't help but invest into them. Also, there are some hilarious points too.

Dragon Age: Origins, to me, has a lot more personality than Oblivion. At least that's how I feel so far. It just sucks you in.