Where it fails is with the puppets, The TaunTaun dying looks awful, the stop-motion there needs addressing as it isnt fluid.
Same with the minocs, they look like bits of cloth on wire.
The cloud city CGI needs looking at, as its computer game standard by modern terms. Im not sure if its possible to retexture map it.
I also agree some kind of scene showing how the ATATs got to the surface would be great. As for now they just appear. Surely they mustahve some kind of Transformer type element where n space the4y just look like cargo boxes. Probably too ambitious though.
ROTJ needs alot of love though (muppet dance sequences, rancor still looking stop motion-y, burps, bad ending with HORRIBLE music), keep the sarlak monster, it was a controversial change but i like dit, formally it was just a dodgy looking rubber hole in the ground.