MGS4 framerate ~27 FPS average.

[twesterm]

I've seen really small dips in framerate here and there in MGS4 but nothing that would make me say it actually has framerate or have any sort of negative opinion performance on it.

As long as the game consistently stays about the 24-25 FPS mark that's good (note that this rule wouldn't apply if the game were allowed to run above 30FPS).

-edit-

As long as the framerate stays consistent and it doesn't dip to something really low like 20FPS having an average framerate of 27 is good.  Now if the game went up to 60 FPS and occassionally even dipped to 30 then it would look terrible.