The Mavis is a simple but great sounding Eurorack voice, rather than a standalone synthesizer, which I suspect is the reason for the relatively low price.
I got this as a companion for my West Pest, and it works great for that, adding a ladder filter and an ADSR to the very basic, but great sounding West Pest. I wish it had a few more patch points, so you could use the filter and the VCA separately for example, but in the context of enhancing the West Pest it works perfectly.