It uses a pretty unique viewpoint, with every moment shown not from the perspective of a narrator, but instead from that of the characters. Be it a camera, a gunsight or a radar screen, you're seeing what the characters see. It makes the combat a lot more visceral than even the most hard sci-fi real robot shows, because you're on the ground and seeing the fighting right there. An early skirmish in which the lead mech engages a small insurgent force is given a shocking power thanks to the viewpoint - the gunsight of the mech's minigun. All you hear is the sound of the gun firing and the pilot reporting the status of the mech, and all you see is smoke and muzzle flash. It won't appeal to people looking for constant exciting action, but it is very atmospheric.
The plot of the series is less real robot and more redolent of Modern Warfare or other contemporary war movies or video games, set in an ill-defined oriental state and following a UN black-op fighting to end a civil war. The tension between the press, the UN and the locals is covered in detail, as is the human cost of asymmetrical warfare. It's attempting to be serious stuff, and does it well.
The ending of the show is very powerful in its own way - some people consider it unconvincing but its suddenness is what gives it power. There's a lot of Takahashi's earlier work in it, especially the comparatively strong anti-war message (for a mecha show) of Dougram.
In terms of mechanical design, the main mech does a good job of seeming like a piece of early 21st century military hardware, taking design cues from modern armoured vehicles. A second mech introduced later is less convincing, though, but interesting in its own way.
The combat scenes aren't exactly dynamic or mobile, but instead interesting in their use of tactics, the tools of modern warfare and the show's unique viewpoint.
Another challenge to tradition is the lack of an opening song, which would seem out of place in a serious series like this. The ending song, LIGHTS, is very good and used excellently in the final episode as the show ends.
In conclusion, FLAG is a challenge to the mecha genre which can be seen as the culmination of what Takahashi attempted in his earlier works - a mecha show which doesn't glorify either side in a war, and which really gives some prominence to non-combatants, maintenance and engineering and military strategy on certain levels.
