Ben turning out to be the final bad guy was not unexpected. It was merely unnecessary. The "best friend is actually the secret enemy" is a trope done to death and it is no longer surprising to anybody, nor is it a good way to finish a story. It seems that the writers thought that more twists automatically mean better story, and that is never the case.
Other than that, I thought the series was ok and fun. Not perfect, of course. It requires some really serious suspension of disbelief. The flashback scenes were needlessly numerous and long and the secretary of defense's motivations and actions ultimately felt thin and unbelievable. Still, if they didn't do the final stupid twist for the sake of twist it would have been quite enjoyable. This way, it is still an alright watch, but the ending ruins it.
Other than that, I thought the series was ok and fun. Not perfect, of course. It requires some really serious suspension of disbelief. The flashback scenes were needlessly numerous and long and the secretary of defense's motivations and actions ultimately felt thin and unbelievable. Still, if they didn't do the final stupid twist for the sake of twist it would have been quite enjoyable. This way, it is still an alright watch, but the ending ruins it.