Judging by the threads here people do still play Oblivion every so often. Are there any good parts or things it does quite well?
Having replayed it last year for the first time in a long time, I'd have to say no. The quests tend to be much better than Morrowind's in terms of structure and variety, and there's a couple of genuinely imaginative scenarios but that's about it. The good parts aren't very good because everything's hampered by awful writing and the infamous all-encompassing jankiness that makes nothing work properly, and almost everything devolves into violence, which wouldn't be as much of a problem if the combat wasn't so floaty and tedious.
Other than that, the moment-to-moment gameplay mostly just consists of pointless busywork like the other post-Daggerfall TES games*, but the core gameplay systems are worse than Skyrim's and the setting is infinitely more dull than Morrowind's, with outright retarded writing to boot. Oblivion's overworld is also much worse and more empty and boring than the other two games. Playing it ultimately just invokes a feeling of hollow sadness, and you're constantly asking yourself why you're wasting your time with it.
It's not really worth replaying, even heavily modded. I'm saying this as someone who has a pretty high tolerance for this stuff and could probably just about force myself to play through modded Fallout 3 again if I really had nothing else to do. Oblivion's just a boring failure with nothing really to redeem it, same sort of affair as Fallout 4. People will tell you that the Shivering Isles DLC is worthwhile but this is a trick, it's better than the base game but it's still deeply boring and pointless. Same for the Dark Brotherhood quests - they are a step up in quality from the rest of the game, but they still really just amount to a couple hours of walking around empty fields and barren "cities" (aka five houses) in order to reach a quest marker and activate some scripted event that ends up not working properly, glitching out, and killing the nearest man with a physics glitch that makes him go "OUUUGH".
I remember being wowed by Oblivion's graphics and the scale of its world at the time it came out, but like all Bethesda games, it generates goodwill through what it
could be rather than what it is. In 2006 it was easy to go "wow! i can go anywhere and do anything! wow! games are going in a great direction! imagine what games will be like in 5 years!" but with hindsight this mindset is obviously all torn to ribbons. I don't think time has been kind to any of the TES games.
*Daggerfall is, of course, the king of pointless busywork, but I'm talking about the specific kind that Morrowind introduced, where you spend most of the game running back and forth through a small and featureless worldspace that feels totally lifeless and static