I have the original trilogy's original version on VHS still, and just recently watched them. I would say they hold up very well and weren't really in need of any post release changes or updates. The effects look great today compared to some other movies that actually came out later, probably because Star Wars used more practical effects vs some early Sci-Fi CGI that ended up not aging as well.

The changes are mostly just window dressings around the original footage, like extra CGI in transition scenes. They don't really change much of the core movie experience. It does end up causing some funny side effects though. Like when the main characters move from one place to another you'll see a splashy dinosaur like creature or fancy robot, but once they actually arrive in the scene the background falls back to the original with a lot less of that added CGI action.