I finished Oblivion, and overall, I really enjoyed the game. The game was pretty, it looked great on a 22" widescreen monitor, had a smooth and addicting gameplay. Its only draw backs is that the main plot got a tad tedious near the middle and end. Also, my normal approach of power leveling to make the fights "not a challenge" didn't go very well because the world scaled. I hate games that scale. The defense was not to sleep, you basically get the effects of leveling (minus hit points) without letting other creatures level up. I think something like the Oblivion Overhaul would work better so you have areas that are actually a challenge until you level up.
One nice part is that you don't have to level. As a first level character, you are pretty much kick-ass and remain that way throughout the game. Playing a fighter type, as I usually do, meant I kept up with the same basically strategy throughout the game. Get a weapon, run up to opponent, squish opponent. Except for the last fight, I didn't bother with anything other than a simple healing spell for the entire game. That as Restoration was my primary skill, but they dialed back the advancement of that by a LOT.
The plot system was nice. You could (and did) stumble across plots almost constantly, people asking you to help or doing something. The quest feedback, which showed your target on the wide-range map, the local map, and also in the compass, was probably the most wonderful parts of the system. Also the ability to switch quests, to switch which quest you were working on was very nice. I would have liked to see the numerical-based quests changed, such as "I have collected 5 of 10 Nirnroots" instead of "I need to find Nirnroots."
Most of the plots were go find something and bring it back, with "something" frequently being on something you have to kill. They had some nice stealth-based plots, which added some mix. However, in the "mage" quests, I solved everything with a hammer and jumping, didn't use a single spell throughout all six quests (I stopped once I got to the university though).
The fast travel system was nice, but I rarely used it. I was usually content to walk from place to place, just to see the endless points of interest that lay scattered across the world. But, at the end of a quest, when I was ready to head home, they were nice. I noticed there were a couple places that didn't have map markers, shrines come to mind, and I thought they should have had them, even with the alterations that are made later.
The leveling system, I could do without. Actually, I could do without levels period in this game.
Except for the specifics of the gate, the main plot was pretty enjoyable. Admittedly, by the time I got around to it, I pretty much breezed past everything. Smash and grab worked out very well for me. :)
The game itself inspires mods. That part is truly a joy and wonder to play. I had a fair number of cosmetic modifications: new covers for the books, different terrain textures, and the like. It adjusted the game to fit my sense of aesthetics very well and I am truly thankful for that. I also had a couple cheat mods, the worse of them being the "summon chest" because I got encumbered frequently.
Even playing the game, the flexibility of the system they wrote is amazing. I could easily picture myself writing a game that fit their mechanics, but used a different world. A well-designed shell for handling graphics and gameplay. I suspect that I'll keep this on, just for additional quests and modifications, or to start over with OOO and play with a power-level approach in mind. Depending on 4E6, I might actually try to create a game world. However, I'll keep it low-key until I can figure out my limits, or if I could actually do it.
Overall, a damn good game.