Every Elder Scrolls game is more like an entirely new game of its own, with some mild connections to the previous one. I guess in those terms it could be compared to Final Fantasy... i guess... Anyways, They all have a different atmosphere and environment to them, and as such, shouldn't really be compared in that sense. Gameplay unfortunately took a downturn in Oblivion for me, but it wasn't dreadful, now its modded for fast paced, short term battles. Everything is so roided up that you focus on killing them in as few hits as possible, and spend more time dodging than blocking. Took out the repetition by adding more risk from enemies.
One other thing oblivion needed was a little more hand-designed areas, so it wasn't all the same stretch of randomly generated forest. Idk, I'm hoping that I will enjoy the Skyrim environment. Southern areas forested. as you head north more mountains, more snow, and more ruins, I'm glad to see an RPG in the frozen wasteland environment. Its not all that popular I guess because so many are based off of our world, where the far north tends to lack all that much variety in life. Skyrim can have anything up there though, the limit comes only from the dev's imaginations.