Scruffy said:
There's nothing silly or cutesy about his appearance--at least, no sillier than he was in RotJ. It's simply a slightly different appearance, due to the limitations placed upon and inherent to the CGI artists of the time. Perhaps your impression of his personality is based more on his mood than his appearance? Like all creditors and collection agencies, he is relatively friendly the first time he calls to collect--but he means business, and will freeze you in carbonate (or do worse to your credit score) if you don't pay up.

There most definitely is something silly or cutesey about his appearance. He looks like a cartoon, with those cutesey big vulnerable eyes. Are you sure you're thinking of the 1997 Jabba and not the 2004 version? In 1997 the animation cutesifies him and plays him for laughs. In ROTJ he wasn't silly at all.

It is not a slightly different appearance. It's a massively different appearance.

Nor is it due to the limits of cgi at the time. The limits of cgi didn't make it necessary to make his eyes big comical-cutesey-vulnerable things or make him come off cutesey-comical in general. That was a choice they made. They could have tried to make him faithful to the ROTJ Jabba. Instead they chose to go a totally different direction.

My impression of his personality is based on everything in the portrayal and his appearance is a big part of that. As for his different mood, different mood doesn't excuse a totally different personality. Even in a good mood ROTJ Jabba would have been menacing. 1997 ANH Jabba couldn't scare a toddler if he tried.