I agree, Oblivion has a much better leveling system, since you actually had to use the weapon to get good with it.
If Oblivion's level system had been *balanced* and not so horribly tilted that you had to grind sneak or spell casting, even when you used it all the time in normal play... then maybe. Instead, you had skills that just wouldn't keep up with your level and you had to spend time training them.
Frankly, I think Oblivion's skill and level up system belongs on the ash heap. It might have been salvageable if only the first 5 points in each level were auto-assigned, but you could move the other 5 points around. Or if they gave you a full pile of points to assign even if you didn't min/max your activities during the previous level. As it was, if you didn't want to get behind the monster's level-up curve (since they all leveled up when you did), you had to install mods to track how many points you had earned since your last level. Just so that you wouldn't be shooting yourself in the foot by dumping all your points into Barter or getting a really low boost to your stats due to lack of focus.
When I installed Fallout 3, I was pleasantly surprised by the use of a XP-oriented level system where you could pick your perks and drop points into skills. It felt right, it felt natural, and it was a whole lot easier then the frustration that was Oblivion's leveling process. That's not to say that it couldn't be tweaked, but I don't miss casting a spell over and over or having to go hack at a dummy for an hour just to get a few points in a skill.