The free demo comes with Syntorial’s fully featured synth so you can try it out and get familiar with it’s full capabilities.
To check out the synth, open Syntorial, and then:
    Mac/PC: In the Options menu, select “Launch Standalone Synth”
    iPad: Tap the Menu button at the top left, and select “Launch Synth”
Here are the specs:
  • Subtractive synthesis
  • Three Oscillators (Two with Waveform, Pitch, Pulse Width, and Mix controls, and a Sub oscillator with Waveform and Volume controls)
  • Saw, Pulse, Triangle and Sine waveforms
  • FM knob
  • Noise Oscillator
  • Oscillator Sync
  • Filter (Low, Band and High Pass) with Resonance and Key Tracking
  • ADSR Filter Envelope
  • ADSR Amp Envelope
  • AD Modulation Envelope
  • LFO with four waveforms, seven destinations, rate, amount, trigger, and mono/poly modes
  • Mono and Poly Voice Modes
  • Portamento
  • Unison with Voice, Detune and Spread controls
  • Ring Modulation
  • Distortion, Chorus, Phaser, Delay, and Reverb effects
  • Mod Wheel, Pitch Wheel and Velocity controls
And here’s a pic: