We have them both, the newer style Frē with the earphone jack attached for my wife's 5S, and a N??d for mine. Aside from the fact that her case is teal, and my case weighs just a tad more, they both function fantastically. I have yet to have a conversation with her and think her phone sounds muffled at all. No one else has complained of it either.
Muffled music is a given.
She has a full screen protector installed underneath her Frē case, and we have yet to have any issues with rainbows or rings (knock on wood).