I point again to Lego Star Wars. Very simple graphics but everyone who saw it that day commented on how good it looked. I'd rather have simpler graphics at higher constant framerates than PC style randomised framerates depending on what's going on.
Its also depends on what game you play. With racegames 30Fps just isn't enough because it's all about reaction and precision. Some other type of games can happily do with 30Fps.