Me ranting a bit.
Oblivion can be fun, but it got too many design flaws. Too many of these flaws can "gimp" your character for later play. These flaws limit the effective late-game choices players have... unless you mod oblivion quite a bit, wich is kind of a chore too.
The worst imho is the way the combat is balanced (the way warriors/ thieves/ mages are effective in the game with their respective tools)
The game is playable/beatable.. when you are a mage. Vanilla or modded (like OOO mod), after a while it became way too clear to me that the game doesnt want you to be anything but a mage;
Bows, even while sneaking around for extra sneak-damage-with-poison, are too weak. All ennemies end up looking like porcupines, and then quickly close up the distance with you.
Its only usefulll use of bows is to kill very weak opponents in one (sneak) shot, or as an oppening move against strong ones with a Sneak-poison shot.
I find this dull, because a bow by itself is hopeless. And i usually like to use stealthy ranged characters, with as little magic as possible, but its not working in this game.
Melee is so-so, but again, you will slash bad guys hundreds of times to kill any serious ones. Too long, but when they melee you.. or there are more than one at once, you are in trouble..
Then magic.
If you played DnD 3rd Editions, well, its basically the same problem in oblivion.
Mages can do everything rogues and warriors can do, but better in every possible way.
Open lock? Spell for it. Sneak around? Invisibility. Defense power? Shield spell. Convince someone to talk? Charm spell. Need more mana or HP? Fortify magicka/hp spell. Kill something tough? Fiery-electric-ice bolt spell.. and you can easily tweak it to scale it to your opposition.
Magic makes many skills obsolete.
With a bit of tweaking around, you cant lose. YOu can create spells that make you immune to everything, lets you destroy groups of opponents, make you permanently invisible, kill ennemies quickly with devastating combo-spells. A bow or sword with magic is just there for cosmetic value, only magic matters.
Really, its the only way to be effective and "competitive" from the mid to high level play. and that is a huge balance problem IMHO. Warrior or rogue, without heavy use of magic, is useless.