These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Animation Age Ghetto: Siskel and Ebert seemed to go back and forth on this, Ebert even debunking it during his review of Ratatouille. But then again they fell into the ghetto with their review of An American Tail where Ebert insisted that kids can't handle a movie filled with pathos.
Ensemble Darkhorse: Of the guest hosts following Ebert's departure, A.O. Scott and Michael Phillips seemed to live up to this trope well enough (to the point where they ended up serving as the permanent hosts in the year after Ben Lyons and Mankiewicz departed).
Even Better Sequel: One could argue that, in comparison to Ebert and Roeper, Roeper's reviews with guest critics (ESPECIALLY A.O. Scott and eventual regular Michael Phillips) produced some great camaraderie that may have surpassed his chemistry with Ebert. One could attribute this to the fact that Roeper's energy complemented critics around his age group more than Ebert (who was roughly 20 years his senior). Roeper and Ebert could view films with different mindsets, given how the latter has listed his favorite film as Citizen Kane, while the former enjoys the broader Ferris Bueller's Day Off (conversely, Gene mentioned in a review that his favorite was probably Dr. Strangelove).
First Installment Wins: No matter the performance of the new reviewers, the original show with Gene Siskel and Roger Ebert is the version everyone remembers.
Gateway Series: This series raised the tastes of at least a few viewers to try films they otherwise would have ignored like Documentaries and foreign language films.
Misblamed: Lots of fans of the show (and Ebert himself) believed that Ben Mankiewicz had been given a raw deal to be paired up with Ben Lyons, and should be remembered for trying his darndest to salvage the show from the mess the execs and Lyons were making.
The Scrappy: One could say this of the entirety of the Mankiewicz/Lyons year.
A multitude of reasons explaining the hate of the Mankiewicz/Lyons era have included:
1) The two having to live up to the precedents of Ebert and Roeper (the latter of whom had actually found a pretty perfect onscreen partner in Michael Phillips after over a year of subbing in guest hosts)
2) The overall lack of chemistry between the two critics.
3) Its adjustment leading to the destruction of the old Siskel and Ebert set, something Roger only found out afterwards, enraging him to no end.
4) The use of a brighter, in-your-face, color palette and opening theme, likely used to bring in younger audiences.
5) The use of gimmicks uncommon during Ebert's run, such as an occasional feature where 3 guest critics would join the two to offer their input on various films in release.
6) Lyons' qualifications in particular were questioned, as he was in his 20s (as well as a regular correspondent on E!News) and some viewers may have found that he lacked the same understanding of film that his predecessors shared. His negative review of Synecdoche, New York earned scorn from Adam Kempenaar (of the Chicago radio program "Filmspotting"), who reflected that Lyons hadn't taken the time to register what the film was actually attempting to say, but rather that the film was difficult overall. Mankiewicz himself averted this, as he's a regular contributor to Turner Classic Movies and descendant of Herman and Joseph Mankiewicz (each of whom were Oscar-winners for writing Citizen Kane and directing All About Eve, respectively), and actually showed himself to be rather knowledgeable about the films they were reviewing.
Roughly a year before this, just as the Bens were getting started, Roger actually published a column relaying the general rules and ethics for film criticism (seen here). Commentators were quick to point out that the timing of this seemed to be a subtle Take That to Lyons, something that Ebert's eventual examination (seen above) seemed to all but confirm.