Everything the show did good:
-Extremely likeable cast of characters from both the hero and villain side. Even side characters.
-Pretty great action.
-Consistently hilarious from start to finish. Managse to make the jokes funny by themselves in spite of being filled with references from past Sentai, but also rewards one for having knowledge of past Sentai shows.
-Great finale.
-Excellent acting in both the comical and dramatic scenes.
-Manage to make the monster of the week feel like a world-level threat in spite of being extremely goofy.
-Hakaizer and Stacy storyline are really entertaining and emotional.
-Aside from Zenryoku Zenkai Gattai Zenryoku ZenkaiOh, the mecha fights are more entertaining than usual.
-The world being fused with Kikaitopia makes the setting feel unique.
-The team doing an unique roll call every episode is fun.

Everything the show did bad:
-The kikanoids rangers feel heavily shafted compared to Kaito, Zox and Stacy. Makes them feel more like the sidekicks of Zenkaizer rather than a proper Sentai team.
-Gaon specifically feels even more shafted because he doesn't get a proper backstory to give weight to his hate of kikanoids.
-The true main antagonist kind off came out of nowhere.
-As funny and likeable the villains are, aside from Stacy and Hakaizer they still feel kinda shafted, especially Boccowaus which felt that he couldn't use most of his powers.
-Zox's storyline feels pretty detached from the overall plot.
-The final mech Zenryoku Zenkai Gattai Zenryoku ZenkaiOh pretty much never looks well on screen.
-Stacy loses too many battles to be taken as seriously.
-Stacy storyline gets dragged. Personally didn't mind it because the show continued to be entertaining but it's still an issue.
-One could argue that Zenkaiger powers don't have much identity since it's just powers based on past rangers. As opposed to the previous show that had power like these where their pirate abilities and stylish fighting was more prominent than their legend powers.
-Having the powers of all previous Sentai from the beginning without having to earn them may feel cheap for some viewers. Especially considering that the previous crossover anniversary show Gokaiger had to earn all the mech powers.

Reasons for the show strenghts:
Producer Shirakura wanted to make the show stand out and came up with a crazy setting. Junko Komura is really good at choosing cast members. Kaito and Stacy actors especially are really good.

Reasons for the show flaws:
Producer Shirakura wanted to emphasize dimension travellings but Covid made it so that they had limited sets available, thus only being able to do that for a few episodes. Main writer Junko Komura was brought over after almost every single core idea of the plot had been decided so she had less freedom. While I understand why Shirakura chose Komura due to the setting being similar to Zyuohger and Akibaranger where she was heavily involved in both, she's bad at handling multiple characters, so she only really focused on Kaito, Stacy and Zox while leaving the other characters behind. The true main antagonist coming out of nowhere happened due to a controversy with one of the villains' voice actor, forcing a retcon as to why it had multiple manners of speech.

Overall:
The show is objectively a 7/10 due to the underdeveloped cast. But the comedy is on point, it's not the funniest Sentai as Carranger had it beat on that regard, but the show never had any big issues to drag it lower. However comedy is subjective, I recommend to watch the first 3 episodes and if you liked the comedy stay watching, just don't go up excepting a particularly complex plot.