Here is my list of changes from worst to best:
1. Greedo shooting first. Aside from the fact that Greedo is blind, Han is shown getting his blaster ready under the table, so George's reasoning for the change doesn't make sense. If he never had the intention to shoot first, why was he getting ready to shoot?
2. Changing Boba Fett's voice. For whatever reasons, Boba Fett is a cult favorite and changing the character's voice was just stupid.
3. CGI Jabba in Star Wars. Blech.
4. Luke's screem in Empire, which was thankfully cut out.
5. Hayden at the end of Jedi.
6. The scream of "Weesa free!" at the end of Jedi, which is very hard to hear, but still like nails on a chalkboard.
7. Deleting "where's my shuttle" and the shots of Vader's shuttle flying back and then landing on the bloody Death Star from Jedi!!!!! This totally disrupted the flow of the scene and takes away some of the tension in the scene.
8. The entrance to Mos Eisley. Was that supposed to be funny?
9. Ian McDiarmid in ESB- interesting idea, but hated the new dialogue plus the Emperor seemed to be drunk.
10. The extended celebration in Jedi and the removal of the Ewok song
11. the explosion "rings"
12. the cgi wampa
13. cgi sarlaac pit
14. cgi cloud city changes made when Lando makes his evacuation announcement on Cloud City
15. cgi effects during the battle of Yavin
16. the scene with Biggs added in
I left out some of the smaller changes (like the Falcon taking off from Mos Eisley, the new shots of Obiwan's house and the Sandcrawler)