I was never a big Star Wars fan but when I first saw the new scene it just felt off. You got old Obi Wan and a very young Anakin.
Don't get me wrong, I wasn't crazy about Sebastian Shaw as a force ghost. I always thought that had Darth Vader not become a robot, he would still look like a tough old man.
If they were going to put in young Anakin, they should have took out Obi Wan and put in Padme. I know it makes even less sense, but visually, it's smoother.