If you want to compare two cgi creations with 2 entirely different results look at Jar Jar binks from the phantom menace vs gollum from the two towers and return of the king by peter jackson.

In the later case Jackson's animators went for the humanity of the character as delivered by Andy Serkis and understood the nuance of a cgi character and to make him seemless with the live action actors.

Instead in star wars jar jar was over the top slapstick and drew annoying attention to the fact that he was an out of place cgi character.

Excellent point. Seems to me that Jackson's approach to CG characters was to make them as lifelike and believable as humanly possible, while Lucas' approach was to make them look as unreal and absurd as possible. Gollum looks pretty incredibly realistic. Cave trolls, orc hordes, the balrog...though obviously fantasy creations, they look like they really could exist, in a more mythical world.

SW creatures, on the other hand, just look like cartoon characters. Jar-Jar's bug-out eyes swivel around like a cartoon frog. Everything about him - his appearance, his movements, his voice, his dialogue - would be more at home in a road runner cartoon than in an epic Space saga. Dex's four arms and airbag chin, the willowy and lighter-than-air kaminoans, that stupidly over-the-top lizard thing on Utapau, that Jedi council member with the giraffe neck (that couldn't possibly support the weight of his head), the Fraggle-Rock reminiscent podracers...everything about these characters seems designed to terminate suspension of disbelief and pull you out of the illusion. "Look! Look! We're CG!! How silly and crazy our anatomical dimensions are! Ha, ha! Look, now I'm defying gravity and doing a quadruple-backflip in midair, just like Bugs Bunny might do! Isn't this great?!"

CG can be done right, but it must be approached with the aim in mind that it look real. The PT went instead for whacky cartoonisms, so its brand of CGI utterly fails to effectively "sell" itself to the viewer.