I use Cubase and record vocals through a good quality studio mic. This simple little device does all it's claimed to do, and you can even see the difference!
I did the obvious thing when it arrived: recorded the same vocal line without, and then with, the pop filter. Not only are the normally hissy and annoying sibilants smoothed out, but those unfixable plosive bursts are also done away with completely.
Often after recording, I previously had to open up vocal tracks as waveforms and drop the gain and play with the EQ to get rid of all the annoying sounds (and never completely successfully). If you look at the waveform of the recording with the pop shield you can actually see the difference - the whole thing is smoothed out, less spiky, but without losing the dynamics of the voice. There is a very slight loss of volume visible, but you won't hear the difference.
I'm happy with the product, and for the money I can't think of a good reason not to get one. Nothing else will improve your vocal recordings as much for such a small outlay.