I've been a musician for over 20 years (bassist), and this is easily one of the best, most revolutionary tools for musicians in songwriters in years! For one thing, it does exactly what is advertised.
I use it in my Pro Tools MP 9 rig, but I mostly use it as a stand-alone tool for practice. Whether I want to play guitar or bass, I can call up one of my favorite tones, and play for hours. I highly recommend this product! The expansion packs are equally impressive.