I never actually got on with 4/for answer. The story is great, and the music is even better, but the gameplay wasn't the kind I could get the hang of. Looking forward to trying Armored Core 5 though. Hoping for a Nineball reappearance.
Best parts of For Answer were using the massive detachable boosters to get to far-off mission zones. You had to dodge incoming fire while going at insane speeds. Far more fun than it sounds.