I've heard the 488 sound from both inside and outside.... compared to my 650S, I must say: 

The pitch of the sound in each gear sounded the same as 650S

The sound inside of the cockpit is just as loud as 650S

The sound outside of the car is louder than 650S in idle

The sound outside of the car from a launch mode to approx.150k/hr observed from a stand point: a bit louder when reaching high RPM on each gear.

Conclusion: 488GTB sounded a lot less vibrant than 458Speciale.... I don't know why most critics saying sounded good, or some people said "similar"  Even Chris Harris said it sounded good....  BECAUSE IT DOES NOT!!  it sounded the same as 650S which I never enjoyed from my car..... 

Is it faster than my 650S? I wasn't the one driving it so I didn't know, one thing I can be sure is that its much much much faster than 458Speciale... That is for sure.   650S and 488GTB are two very similar character cars now. 488's soft rear damping around the corners are a bit neutral (while I wasn't the one driving it, I can feel in sharp fast corners the softening damping helped get that grip in).  McLaren's break steer I must say works better to tackle the corner, but a bit too much electronic and takes time to get use to, feels unnatural.  

I must say Ferrari would still sell a great numbers of 488 even though the turbo had changed its character of the car. I must say Ferrari has to since this sector market is all about figures, performances.  As long as they keep their F12 (V12NA) its all good!!!