I have one, though its going on over 15 yrs old. From what I remember, the pro's: Wiggy offers a WIDE version, which is a nice feature if you're a claustraphobic sleeper. The batting is overlapped to avoid cold spots, which is a common feature today but not in the 80's and 90's. Also, unlike other synthetics from that period (such as Qualofil), the batting Wiggy used didn't suffer as much from being compressed for long periods of time. It seems like most manufacturers recommend storing their sleeping bags uncompressed when not in use to avoid long term damage to the fill. Makes sense, and I try to do that with most of my sleeping bags, even the ones with goose down.
Unfortunately for work purposes, my bags need to be kept packed all summer long and I can't store the sleeping bag in an uncompressed state very easily in the back of a truck or equipment locker. The Wiggy was good for this. In fact, the Wiggy now resides in the trunk of my wife's car for emergencies.
From what I remember, the Wiggy I had was a good 3-season bag, though I would not want to winter camp with it. Not sure what different ratings Wiggy offers these days, but my rule of thumb has always been: If the manufacturer rates it as a 30 deg bag, in the real world it is good down to 40 degs, 15 deg back is good down to freezing, and 0 deg bag is good down into the 20's. For a while there, I had a theory that the manufacturer's recommended degree rating was in CELCIUS!
Hope this helps
