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.
YMMV: Tensou Sentai Goseiger
Awesome Music: Despite the series not shining as much as the recent predecessors, at least up to the first one-third, its soundtrack is definitely on par with others'.
Gosei Great's theme song, "Kōrin! Gosei Great", is a must track.
Broken Base: How Western Sentai fans feel about Goseiger. They either like it and the throwbacks to previous Sentai series (including Zyuranger, Dairanger and Magiranger) or they hate it because of bad characterization, uneven writing, gimmicks and reliance on them. Things cooled down once Gosei Knight joined the cast, but the show is still subject to intense scrutiny.
It doesn't help that it came after the highly acclaimed Samurai Sentai Shinkenger, and when the double whammy of Power Rangers Samurai (the return of the series) and Kaizoku Sentai Gokaiger (pirates, nostalgia and sheer awesomeness) hit in late 2010, they completely overshadowed Goseiger (Although in the case of Samurai, it's because it's commonly seen as a terrible season).
Points generally used in favor of the series include its awesome mecha fights and interesting villains, but offset by criticisms of its weak heroic cast and bad writing.
With the confirmation that the series is to be adapted as the 20th anniversary series, Power Rangers Megaforce, instead of the much more desirable Gokaiger, the criticisms are starting again. Though it was later eased somewhat when it was revealed that Megaforce would combine Goseiger and Gokaiger.
Special Effects Failure: Buredoran of the Chupacabra's claws are clearly EVA or a similar material, given how impossibly flexible they are whenever he moves his hands.
Squee: A blink-and-you'll-miss-it moment in Epic 21. Takeru (not that one, or the other one), the boy who ordered the birthday cake that Eri's rushing to complete, shows up with his baby sister Hiromi, saying that the cake's for her first birthday. The camera pans over, and with uncanny timing Hiromi smiles into it. Cutest. Thing. Ever.note Of course it's probably just the baby's Real Life mommy making faces beside the camera...
They Wasted a Perfectly Good Plot: The origins of Knightic Power. It was never really explained. It would be really cool if it was related to a secret or ancient tribe. The same applies to Gosei Knight, who could perfectly be a lost ancient warrior from Gosei World instead of a Sentient Headder.
During their battles against Warstar, Alata had personal battles against Dereputa. The same kind of happened between Agri and Kingugon during Yumajuu arc. Why couldn't we have the same during Matrintis arc, but with Hyde? His water based powers and analytical strategic mind would be used in a great manner if put against a stronger Matrintis's general.
More use of combined elemental attacks would be interesting, like Wind+Ice or Water+Land or Thunder+Water. Those could be used in several creative ways.
Magis, who created a lot of fan speculation, ended up being not very important outside of a few episodes.