The question is far too broad for a simple "yes" or "no" answer. I tend to fall on the "no" side of the argument. If you read Clauswitz, Liddel-Hart, Keegan and Thucycdides, you'd be bound to say no, because of the tremendous continuity in war over thousands of years. Motivations for going to war haven't changed. Fundamental strategies haven't changed. The psychology of combat hasn't changed. The limits of human perception haven't changed. The extent of our errors hasn't changed. It remains, as David Byrne said, "same as it ever was."
What has changed is how and why we use war. I don't just mean in terms of technology or doctrine. Yes, an M-16 is not a spear, but that's a superficial difference. What's really distinct about modern combat is its indecisive nature, which is a consequence of the new ways that wars are being fought, as well as the disconnect between a nation's policy leaders and its military goals and methods.
You should read Victor Davis Hanson's The Western Way of War. According to Hanson's thesis, the Greeks invented the decisive infantry battle as a way of limiting the destructive potential and duration of wars. The West adopted the overall pattern of this type of warfare, but we've lost the sense of the overall purpose of it all. Of course, if you trace Hanson's continuity of warfare from classical Greece, it shows how much things have changed from the warfare of the earlier Greeks as represented by the Homeric heroes.