What I've noticed:
-More Flare for the Probe Droid engines
-All images through "binoculars" replaced
-Return to Wampa never seen clearly during the cave scene (though I think Adywan put in his own visual there)
-Added visuals for speeders' instrument displays
-Some action for the AT-STs during the Hoth battle (including one getting crushed by the falling AT-AT that Luke destroyed)
-Turret fire from the Star Destroyer that gets Ion-cannoned before it gets hit
-1st transport group jumps to hyperspace
-Less static look to the asteroid field
-Show dust eruptions whenever blaster fire or proton bombs strike asteroids.
-Some digital facial enhancements for Yoda, mostly in the mouth (Very well done in my opinion, so much that I almost missed it)
-Spider from "Star Wars Rebels" on Degoba (not my most favorite addition)
-Editing of Special Edition's Vader-Emperor conversation to that it matches the original while retaining the new Ian McDiarmid visual and voice.*
-Less tailgating by Slave 1 during the Falcon pursuit.
-Return of original "Bring my Shuttle" line from Vader during Cloud City withdrawal rather than the changes for the Special Edition, as well as removal of Vader's arrival on the Star Destroyer.
-I know from Adywan's own progress posts that some considerable work when into the Falcon Hanger scene on Hoth, as well as the Wampa scenes, for which he underwent considerable frustration.
That's all I can remember right now.
*The Palpatine change for the original Special Edition is one of the things I approve of in concept, but laud in its execution. The image of Ian McDiarmid might as well have been the false face of the Balok puppet from Star Trek TOS for how animated it was. It was just McDiarmid's voice, his face, and moving lips. Although Adyway could never have gotten ahold of Ian McDiarmid to redo that scene, it is one of the things I wish he could have.