Just got back from my test drive, and my official opinion of the sound symposer is:
Meh. The car is just so damn quiet, its near impossible to hear or feel the engine. The symposer kicks in around half throttle, and sounds good, it's a deep warbley wuuhhh sound, but it's a bit like an on/off switch. They could have "blended" the sound in better somehow. But, am I glad they put it in? Yes, because it would be whisper quiet in the cabin without it. Would a louder exhaust be nice? You bet! But still I think my "rough", crude, loud, Borla'd SVT engine has more character than the ecoboost, because it is much less isolated from the driver like the ecoboost is. I'm sure it would grow on me if i owned it though.
Mine: 2004 Subaru WRX Wagon: 116k, WRB
Gone: 2002 SVT, #1654
Hers: 2012 Focus Ti Sedan: 67k, SGM, Manual