Great, I'll probably finish it in a few weeks at worst. I cannot stop here, too awesome.
I read all part 4, 5 and 6 last month (and I read late part 3 last July) and I can say I never enjoyed reading a manga so much. I'm more a anime guy, fighting scene are sometimes tedious to read and it's better with colors but I don't care if it's Jojo.
I don't know the general opinion here but I'll put part 3, 4 and 5 in a draw for the best parts for differents reasons. Part 3 has the weakest stands but the road trip atmosphere, the cast and the final battle make it great, especially in the late part. Part 4 because it was the funniest and the stands got crazy. Part 5 because of his amazing pace, Italy and also the greatest fights in the series in my opinion.
After that I guess it's Part 2 because of Joseph and after Part 6. Jolyne is one of my favorite Jojo but the fights felt a little bit confusing, the prison was not the most charming place in the world and the main antagonist is probably my least favorite one (I actually thought it was mid boss like red hot chilli peppers but nope). Part 1 is the last one because the only saving grace for me is Dio and that's it.
But anyway, I'm amazed by the creativity of the whole series. It never gets old, Araki find always something new that makes me want to continue and even the oddest stand can be well executed. It just becomes one of my favorite thing in a cultural media