This is a surprisingly versatile (mono) synth, capable of quite a wide variety of sounds – not just acid-y basslines (although naturally it's great at those).
There's a good selection of oscillator waveforms available, and the Sync and Ring Mod modes can produce some unexpected variations on the basic sounds.
The onboard FX are excellent, and very usable.
The supplied pre-sets are good – but the Tau Pro is fun to program, and you'll soon have made a bank of your own sounds anyway.
On the one occasion I contacted Muon customer support, their reply was quick, courteous and helpful.
The Tau Pro has a couple of limitations to be aware of: there is no ADSR envelope generator, and pitch-bend via MIDI is not implemented. In practice (and in my opinion), these don't detract much from the value of the synth. However, if in doubt, download the demo, and see how it handles for yourself!