Overall: No one needs this many rangers
Before I say anything else; I enjoyed watching Kyuranger.
This does not make it a good show.
Kyuranger is full of bad decisions and things they just shouldn't of done. The first one is we don't need 12 rangers. We don't need 12 rangers in one sentai, because the biggest fault of kyuranger is that we don't have time for developing 6 of them. It was too ambitious for a single series. Also the tone and pacing was a complete mess.
Sadly, I have set these up where I give my opinion of Every ranger.
I don't know if I recommend Kyuranger. I recommend certain episodes and arcs, particularly Stinger's and Balance-Naga's. Everything else is kind of just too messy for me to fully want to recommend and it has so many problems in every aspect. If you like it, as I do, I don't judge you though.
List of Series
Lupinranger vs Patoranger