Well...how about why the hell did the Rebellion have to assassinate Mads Mikkelson's character. (its not a spoiler) It just made little sense. If they succeed nothing changes and if they dont those characters probably die wasting them completely. I get his purpose to the story and that is fine, but the whole attempt to kill was dumb. It was a stupid method to manufacture drama between two characters that was neither believable or needed.
Forest Whitaker was a waste. His character was lame. As was the stupid Empire Guy who just happened to always be wherever the Rebels were out of nowhere so he could witness everything go wrong and Grand Moff CGI could insult him.
Why did we go planet hopping for the first 10 minutes of the film?
Does the Empire not defrag their hard drives? Always delete your backups.

(if you have seen it you know what I am talking about)
Does the end take place 5 minutes before A New Hope? If not the ending makes almost no sense? If so then the beginning of A New Hope kinda is off too but only in a nitpicky way.
The robot started out cool and got old after "quirky quip #75". Hey tell us the odds again...
Actually that one was the ultimate sin for me...the Christopher Nolan-esque beating over the head of call backs to the Original Trilogy. (Nolan doesnt just tell you once...it has to be done 50 times) Lucas did that with the Prequels too...we get it they are connected. Stop with the "I have a bad feeling about this" style stuff. Give your audience some credit you dont need to hold their hand through everything they get it. Hell they must have mentioned a certain exhaust port 35 times in the movie which took away the coolness of that fact in ANH.
Honestly the flow of the movie sucked because the first half just draaaaaaaaaaaaaaaaaaaags. When things actually start happening and there is real plot and spectacle the movie is great. Honestly a few story changes and it probably rates #2 for me. (right now it is 4 or 5 depending) My changes in white:
First off start the movie the same way with her as a child. That is fine. Even have Forest Whitaker save her like before. Instead of having her then show up in prison for no explained reason (I think that is where she was) have her still with Forest Whitaker and his band of hardcore rebels. Have the Rebellion reach out to him to join the Alliance and have them have the message from her father. Have the Whitaker Crew be the only survivors of the Death Star attack on the stupid Jedi City. Instead of the stupid duel story of wanting to find her father/scoundrel wants to kill her father just have them search him out as he has been a long term spy. Then when they find him the same Empire Guy who took her father from before is there and the battle ensues. (In this version it happens much earlier so there is more action throughout the film making it much less boring.) Daddy dies but gives her the plans without saying he created a flaw just saying it can be defeated...they no longer needed to be stolen from the backup files on Random Planet #6. Have them need to go some place to decode them...some place deep in the Empire which leads to the climactic battle. Or have it on Random Planet #6 just have it be fore a better reason than needing to hack the Empire's Cloud Account
) Have Grand Moff Tarkin send Vader to kill Empire Guy and to defeat the Rebels with his fleet. Dont give away what the message is until the end by having it given to Leia. Let thee audience make the connection dont shove it down their throats.
I think the movie could have been Empire Level great with a different story. It just fell into too many traps in my opinion. That is why I gave it a 5/6 and my buddy barely gave it a 5. If it hadnt been named Star Wars I think the critics are less favorable as well but that is just a gut feeling.