Aside from the aforementioned broken levelling system (it gets harder when you level up, training skills you don't need is the best way to maximize your attributes..), the hideous characters and laughable animations, the repetitive dungeons, the generic setting and story, the bizarre NPC behaviours, the uninspired writing, and a couple of boring quests, Oblivion is actually a pretty good game. It's certainly worth what it's selling for these days. And, to repeat a common sentiment, the PC mods apparently do a lot to offset many of those problems.
It can be fun to run out and explore, to find different herbs and plants, to sneak into people's homes at night and nick all their stuff, etcetera.. But actually interacting with NPCs can be a real immersion breaker. There are like 4 different voice actors outside the game's main quest, and NPC dialogue is wildly inconsistent--a character will great you with an angry "WHAT?" before cheerfully giving you helpful directions around town, and then angrily telling you to get lost.
It can be fun to run out and explore, to find different herbs and plants, to sneak into people's homes at night and nick all their stuff, etcetera.. But actually interacting with NPCs can be a real immersion breaker. There are like 4 different voice actors outside the game's main quest, and NPC dialogue is wildly inconsistent--a character will great you with an angry "WHAT?" before cheerfully giving you helpful directions around town, and then angrily telling you to get lost.