I ran Whisper for the first time at my weekly store game night last Friday (in fact, as a Rebel player, it was my first time playing imperial) and I found the new decloak rules were very powerful. You sacrifice little in decloaking first, but gain more, IMO.
You give up a very large information advantage under the new rules: you can no longer use the decloak to react to your opponent's maneuvers, and your opponent can reposition in reaction to your decloak.
I think part of the reason for the differing perceptions of the change is that some players were relying on the Phantom's enormous information advantage, and some weren't. If you were already in the habit of planning your decloak along with your maneuver, or your typical opponents were good at predicting your decloak location (or even confining it) and predicting your maneuver, then the change won't make much difference to you.
That doesn't make it a small change, though.