A well balanced and fair review, and I agree with all the comments so far: just baffling why Amazon ever thought this would sell well given all the cheaper and better competition.
Who would buy a Fire Phone given the alternative of pretty much every other phone that's available? And why did O2 take it on? For sure, I don't expect much sense from O2, but even so, this is one exclusive deal too far.
All I can think of is that this isn't really a phone per se, but really the physical manifestation of a very clever tax-offsetting financial derivative.