Ehm... yeah, you know that you just disagreed with yourself? But still, I have to agree with that "adds something so it sounds better". But only if you play into guitar cabs.
Not really, as has been posted before (but can't find the link immediately), a couple of people reviewed it as a small delay in the timing of certain frequency bands, giving a more amp-like feel without actually coloring the sound.
I'm far from an expert, so I don't know if this is true...all I can say is that from personal experience, it works fine with both cabs and FRFR monitors.