I bought this effects unit for my synth mainly because of the following features: it has stereo inputs and outputs, tuner function and an extensive catalog of effects for a reasonable price.
I mainly use the tuner function and modulation effects. The tuner works very reliably with any sound that doensn't have variation in pitch. I first used to provide only sine wave of A 440 Hz to the tuner, but I quickly found out that this is not necessary, as the tuner is able to find the pitch from variety of sounds and notes.
The modulation effects like phasers and flangers are pretty good and I don't find a reason to have more sophisticated separate effects for that purpose. Even if the stompbox is quite small, you can do lots of adjustments to the effects with the parameter knobs. Of course the dedicated classic pedals might be better and more authentic, but as these effects are only occasional added value to the basic sounds I use, this product is more than sufficient for my use case.
As I have separate effects for overdrive, delay and reverb, I haven't used those effects so much but also those categories are nice to experiment with the synth. The overdrives and distortions can provide a nice guitar-like sound. The filter effects are fun to use too.
If I had to have only one effects unit, then this stompbox would not be enough because only one effect can be used at a same time. Then I would look at the bigger models. However it is really great that this low-cost unit contains all the same various effects that the bigger models have.