I bought this so I could use a whammy type of effect, although it does more than that.
So first of all, the sound. It's good, I've never tried the Whammy 1, so I don't know if it's better or worse but, having no reference, all I can say is that all octaves sound in tune, it tracks easily and the bending is continuous. No control for mixing in dual mode (as in the POG), only a blend knob that mixes dry and wet.
Harmonies sound good as well. No minor 3rd however, which might be a drawback for some.
the footprint is small, which is nice for crowded boards, and if you use an exp pedal you can put them apart in your board, which is also good.
Also, if you don't want/have an exp pedal, you can use momentary mode (it as a latch mode on/off switch) and you can calibrate the bending speed (by using an exp pedal, just for a one time calibration)
Very easy to use.
But pricey.
Pros: sound, small footprint, use of expression pedal, or momentary mode (which can be calibrated). Up/down/dual modes allows to choose the octave direction. Goes up to three octaves.
Cons: pricey (and extra if you want an expression pedal), so it becomes more expensive than a whammy. Doesn't allow to control the mix of the octaves independently.
4 stars because of the price, and the lack of octave mix.