In this scene (with the first fly-over of the snowspeeders over the hill);
Maybe you could change the hill to something more appropriate, such as a snow mound as opposed to what looks like a Lilliputian mountain range. Also, would we see the multiple shadows of the snowspeeders on the ground as they fly overhead (I know the angle of the gun turret shadow is pretty long, which wouldn't explain the somewhat "noon-ish" sunlight covering everything - the gun turret shadow would indicate the sun is about the set)
I think it would be pretty cool if you shortened the gun turret shadow (say, maybe a 40° angle shadow on the turret as opposed to 20°), replaced the left hill with more of a snow slope and showed the shadows of the snowspeeders on the slope and ground as they all come over and at us. It could help add to the sense of speed.
http://www.youtube.com/watch?v=JkywRUAd0_w&feature=related
Also (at 6:18), shouldn't the snowspeeder shadows be on the lower right of the vehicles, if we go by the shadow in the above picture?
http://www.youtube.com/watch?v=WAr4PIAZiqQ
(from 3:35 to 3:52)
Also, in the Wampa attack, would it be conceivable to add a bit of blood to Luke and the Taun-Taun (maybe even show blood fly out of Luke's mouth when he is hit), be it in the initial impacts of the Wampa claw and/or when they fall down into the snow. An extra or alternative could also be to add some sound FX to indicate Luke's jaw breaking from the hit as well as the Taun-Taun's neck being broken (celery is a good stand by, if not sampling other movies that have some bone breaking sound FX).
Could also consider adding some bass to the Wampa's claw impacts (nothing too Michael Bayish) - just something to indicate a creaure with the power of an 18 wheeler behind it, and it's hitting Luke and his steed full force. Maybe you could show BOTH of the Wampa's arms and hands as it is choking/breaking the neck of the Taun-Taun. When we see the Taun-Taun (at 3:42) you could show 2 hands grabbing onto the Taun-Taun's neck and twisting (or at least manipulate the Taun-Taun head to violently turn to the right with a sudden SNAP sound FX)
You could also show the Taun-Taun's eyes get wider when it starts freaking out from smelling the Wampa, and/or even see if you could have the Taun-Taun spin it's head quickly to the left (at 3:40) to face the Wampa when Luke gets knocked off (to look at the sudden movement coming from its flank)
You "could" change the footsteps in the background to go from the the center to Luke, as opposed to directly behind him. That would give us a better indication of how far he has walked.
I also noticed at the (3:54) scene in the youtube.com link, the entrance of the rebel cave is somewhat different that the one we see in the rebel transport scene.