Unfortunately, the earlier parts of the series have really not stood the test of time, and Stardust Crusaders, especially given its status as the most iconic part, might be the biggest example of this.
The basic idea is fairly sound: Dio returns after being absent in part 2, Joseph and his grandson Jotaro along with a few other people go to Egypt to save Joseph's daughter and rid the world of Dio once and for all.
To give credit where credit is due, SC introduced the concept of "Stands" to the series, which is much more interesting than the "Hamon/Ripple" of the previous two parts and allows for a lot more diversity and cleverness in the fights.
The thing is, while it may have been good for its time, the characters and storytelling in SC are now honestly pretty lackluster, outside of some entertaining fights it doesn't have anything that you haven't seen done better in a modern shounen 1000 times already. Jotaro is a pretty bland Jojo all things considered, and the rest of the cast is pretty forgettable. Even Polnareff, as entertaining as he can be, pales in comparison to just about any side character in part 4 and onwards.
Stardust Crusaders is also unnecessarily long; it is more than twice as long as both parts 1 and 2 combined, and most of it is just a "monster of the week" that gets dull fairly quickly. You really wish they would just get to Dio already, especially considering that there's no real interesting drama, substance, or character development going on.
The art in this part is improved from the previous 2; characters are still bulky and overly muscular, but they do generally look more natural and expressive. The art is by no means bad, but I can't say it's that much of a high point either unless you really really love the retro fist of the north star look.
There are some pretty good moments, admittedly, such as Jotaro's game with D'Arby and the final fight against Dio, but none of that really makes up for how underwhelming SC is compared to future installments in the series.
Stardust Crusaders IS entertaining and serviceable, but it is noticeably dated. if you want to experience this part i suggest watching the currently airing anime adaptation of it as it makes it a lot more entertaining.
