Been using it for the past few years, nothing bad to say about it, lovely piece of software. Vendor lock-in is very present in this field, with different brands of controllers supported by a myriad of proprietary DJ applications all more interested in onboarding you to their music subscription services rather than implement useful features or support open protocols.

Meanwhile, Mixxx allows you to write your own adapter scripts for any controller you have (as long as it outputs MIDI), and there's a built-in library featuring scripts for the most common commercial controllers and MIDI devices out there.