It's definitely a big deal. I'm nowhere near someone who worries about frame rate, but I noticed it without seconds of booting up game.
It's not the fact that the frame rate is terrible, but the fact that it is constant and drops from 60 to 30-40 constantly.
Initially, i thought it was a design decision when leaving houses, being deep in battle, but nope.
Obviously, it doesn't make it anywhere near unplayable and it's a fantastic game, but to say it's not a big deal would be pure fanboyism.
I mean, I don't think it's a big deal. And I certainly wouldn't say it's constant. Neither would IGN, GameXplain, or USGamer. Like I said, it's noticeable when it happens, but constant framerate drops of 20 or more simply wasn't my experience. Everyone's milage will vary, but to call it fanboyism when something genuinely doesn't bother you is disingenuous.