>>98074208RT was already around when the movie originally came out, so odds are the rating is inflated by the vast majority of the reviews being of the time period and reflecting the defiance of expectations by the fact it was an actually good animated sequel, especially since it was originally supposed to be direct-to-video.
Also it's common consensus around here that TS3 is the weakest, and a rehash of 2. But I'm too familiar with all of the movies to be even able to judge their quality anymore. I have no reaction whatsoever to them at this point.
Shrek 2 is definitely better than the first one though