What follows are my thoughts and opinions...
I have been thinking about the word "Complete". In my opinion, that word is very open ended and vague with respect to martial arts. I think that often times when people say complete martial art, they referring to survival and the knowledge of universal principles of hand to hand combat. However, the listener thinks more along the lines of sport.
In sports, there are rules, the end is determined by time and a few other factors, but certainly not death. The athletes know how long the "fight" could last and there is no real fear for their life. There are specialized techniques that they use to "win" and like-wise by rules there is only so much that can be done. Most times these techniques are adaptations of martial techniques. But neither is going into the competition with the intent to seriously harm, maim, or kill the other one.
For me, from what I can tell, the Bujinkan contains what I consider a complete art for survival (with the exception of eternal life). Human hand-to-hand combat has some very universal principles and BBT certainly has NOT cornered the market on them, as I am sure there are many other arts who realize these principles. However, for me it has everything I could possiby think of and it works for me. I believe it is a complete martial art for survival.
In essence I think that "complete" conjures up all sorts of definitions that are not entirely accurate, especially when the speaker is thinking fruit and the listener is thinking oranges.