I have had the Go! Cutter for a couple of years, and although I don't use it as much as I thought I would, for me it was still a worthwhile purchase.
I have one strip die, but don't use it, as cutting strips with a rotary cutter isn't a problem for me. My favorite die is the small tumbler, then the triangle in a square. That one is nice because there are no dog ears, which makes lining up those of angles really easy. If you're into applique, cutting those shapes (as available through a die) would also be much easier and faster, too.
The reason I don't use mine as much as I could is that I don't have space to leave it out, out, it's in a closet in a different room.
I purchased mine, so gently used that it looked new, through a yahoo group, "sew is for sale. " you can get some good deals on all things sewing related there (as well as well items you no longer want). My dies were all purchased through another yahoo group, "Pins and needles 1." Prices there are always at least 30% off.
Hope that helps!