Not sure if the opinion would be that Oblivion is still playable given its ripe ol'age, but I figured add it to the library anyway. I had it years ago I believe but never did get into it very deeply. I know, my loss, as some folks prefer it to Skyrim.
Oblivion is kind of a weird half-way between the complicated Morrowind and the very easy to learn Skyrim.
It's worth a play, but I wouldn't say it's aged gracefully. The character models are hideous, they didn't even look good at release. A lot of the dungeons feel like 'rinse, repeat' of other dungeons you've been to. Spell effects are borderline laughably animated and equipment repair gets boring. The speech/persuasion system is hot garbage.
But it's got some high points. The fighters guild/mages guild feel more expansive than their Skyrim equivalents. The main quest seems more in line with TES lore (if you care, I didn't). Spell creation, while visually underwhelming is
absolutely broken. Want to kill every monster with 1-2 spells? Lump a bunch of 'weakness to x' followed by 'x damage' in your spell.
Combat is, well, Elder scrolls combat. Expect swishy LARP weapons that don't feel like they have lot of oomph.
It's worth a try, and the modding scene helps deal with some of the worse aspects. The Shivering Isles expansion is nearly universally loved, and does a great job with the Daedric prince Sheogorath, though I'd say Knights of the Nine is my favorite Elder scrolls plot line to date.