It is what it says it is... A GIJoe film spinoff detailing the origins of the mysterious ninja characters from the films.
Its done pleasingly, albeit a little devoid of real grit from the female actors, and it's a film you can get into the choreography and story and enjoy it at face value...
There are a few loopholes and inconsistencies (for example {spoiler alert}: how the actual f@#k does the clan keep 3 giant ancient anacondas fed and alive ffs??) in conjunction with a few sub-par performances, but, overall its a pleasant spinoff and accompaniment to the other 2 films in the franchise, and does so with considerably less focus on firearms and more on the action one might expect to see from a strong culturally Japanese standpoint.
The protagonist and his supporting actor were convincingly good and very well cast, forgiving the occasional slip in a forced faux-American accent from our (anti)hero revealing his British roots, but a near flawless undertaking from the supporting actor in all regards.(Andrew Koji was actually quite brilliant).
As someone who truly enjoys a powerful female character, I feel the casting of pretty-much every female character was not so great, from the grandmother head of family to the overly camp, cartoony feel of the 'she-baddie' and even the random Joe, Major Whatsername (I believe her entire function in this film was to establish a relationship between the Joe's and this ancient Japanese family, and to deliver the spin at the end of the film... Other than that she could quite easily not have featured in the film at all), and the annoyingly over desperate (possible love interest? I dunno, it was fairly poorly played out) Akiko, I was a little let down and thought all their roles could have been cast and performed considerably better by others... But who am I to judge...
Excellent graphics, (though I'd have been far more pleased with even just a smidge of blood and gore thrown in {I mean come on, there's a tonne of fighting with blades and no blood and severed limbs flying around} coz there was all but nothing at all....) the film was worth a watch, sure, if nothing else other than to stay up to date with the film series.