You gotta be kidding me, Blanky!
JE an adventure game? Sure, it was one hell of an adventure, but it couldn't be a truer RPG. The role-playing experience present in JE is surpassed only by the FOs and perhaps PS:T.
Also, how can you say it's very linear when you say it's like Oblivion? Oblivion is pretty much the most open-ened you can get - bordering on a SP MMO likeness.
But you're right about one thing - there are comparisons between JE and ME: Not only have they both ascended to the realm of being totally sweet, but they're also individual reasons to buy their respective consoles alone!