Personally, I just found it way too jarring, seeing these digital effects in a movie that was obviously made in the 1970s/early 80s. This distracted me to know end and lowered my enjoyment of the films. Other than that, I had no problems with them...
... Except for one: That horrible musical number in Return of the Jedi. Come on Lucas, this is Star Wars, not a flippin' Disney film!