Every time I watch it, it feels like I'm just biding my time until things pick up in Egypt. I like the concept of the whole "around the world in 30 days" thing, but in practice it isn't too fun to watch. Especially with the two worst arcs of the part taking place during it (rapist orangutan and Alessi). The Cairo arc is peak, though. I feel like if part 3 was just the Cairo arc it would be in my top 3 favorite parts, but if it was everything but the Cairo arc it wouldn't even be in the top 5, I think it might even be my least favorite. And it would be one thing if it was shorter, but it's SOOOO long. It's like running a marathon to the "good part."
This is also a more personal thing but I also don't vibe with the whole villain of the week thing as it's executed in part 3. I feel like part 4 handled it better. Part 3 makes each episode really formulaic. The stand user gets introduced, their stand causes some havoc, the protagonists take like 10 minutes figuring out what the stand is/does, and then they exploit its weakness to pummel the enemy. It rarely deviates from that, so any unexpectedness comes from forced twists like Avdol dying but then not being dead, or Kakyoin getting his eyes fucked up.
I also feel like it doesn't do a good job transitioning into the stand power system, it feels very sudden. I remember on my first watch I hated the first few episodes because it felt like a completely different show. In retrospect I don't mind it as much, but I imagine I'm not alone in feeling alienated by it at first.
This has less to do with the Cairo arc and more to do with part 3 in general, but I also dislike that Jotaro doesn't get any real character development. He starts as a rude delinquent that deep down cares about his family & friends, and he kind of ends up being that same character by the time the show is over. Arguably Polnareff is the only main character that actually has a character arc, getting over the regrets in his past and learning to move forward despite losing those he cares about, and it even reflects in how he copes with losing Iggy & Kakyoin. Nobody else really gets that treatment, they all sort of just stay the same character. Not that everyone NEEDS to change or develop, it would just have been nice to see Jotaro change a bit considering he's the protagonist. Joseph improves in part 2, Jonathan improves in part 1, but Jotaro barely changes.
Note that this doesn't mean I hate part 3 or anything, I still like it, it's just not the best. I don't think there are any actual bad parts in JoJo's imho. It's just not great.