Toei has argued that Go-Busters was ill-received because of this (especially following the then-recent Tsunami) but I personally believe they should be brave enough to admit when something fails simply because the majority of the fan base did not connect with it, instead of blaming outside factors. Fascinatingly, and thankfully, when a mid-season change in focus was implemented to assuage this, the story continued in exactly the same manner and managed to become even more severe.
While development stalls to a degree for some of the characters in this second act, it still follows a tight, plot-item driven structure which sees the show through to an endgame that features the best mech-choreography I've experienced and an immensely mature, appropriate, and gripping resolution for all but one of the cast.
Go-Busters dwells consistently on the themes of overcoming weakness through partnership (and the family you make), having an acute awareness of what should drive you, finding the beauty in imperfection, resoluteness of action, and sacrifice. These are brought to bear by a relatively small cast of humans in tandem with a wonderful contingent of emotion (and ego) driven automatons that rival and often out-perform the Imagin in Kamen Rider Den-O.
If the ostensive spy motif isn't something that normally captures your interest I would actively recommend putting that to the side as that’s essentially what the writing team does fairly early on. The special task force moniker is far more fitting and a great emphasis is put on scientific and engineering endeavors, as well. In total, the show is so incredibly much about the interactions between the hero characters. The villains of the show are very serial and extravagant in nature (think Dr. Wily) and are allowed snippets of nuance in the endgame, but ultimately exist to set up situations that allow the other characters to grow and shine.
I believe Go-Busters embodies and exemplifies the best Sentai has to offer not only in its characters and story but also in its franchise-defining mecha. Imperfectly perfect.
50 episodes, approx. 24 minutes each.
Their supplemental materials are detailed below the cut.
5 Promises Redefined out of 5
Nutted by NEG.