I haven't, yet would recommend scrutinizing any formulated "method" by asking oneself if the course is based on the following:
- Visual references
- Practicing licks that simply follow the chord changes
- A particular style of jazz rather than general improvisation
Improvisation is literally your playing ideas that come from YOU! That (obviously) takes conceiving of those ideas either through your own creative processes, or having a lot of ideas that you can recall from your mental library which fit a situation. The hard part, which is difficult to teach, is coordinating the ability to instantly transfer your mental musical imagery into your hands to make the music you hear in your head REAL.
Most academic or online "methods" concentrate on visual clues and simply practicing a number of overly worn riffs and arpeggios from 1950s jazz. These are strung together in a cut and paste fashion according to the chord changes in the tune. It's about as far away from improvisation as you can get as none of it is coming from you and you can't hear what you're playing until it comes out of the horn!
If you can sing along with a tune, and more importantly sing variations, harmonies, and add rhythmic ideas, then you're improvising! Practicing playing what you would sing and making it come from your horn is real instrumental improvisation. Practicing playing something that you hear without a visual reference (written music or chord charts), can help with making the connection between hearing notes and playing them without any other reference. I've seen a Youtube video of this as an exercise (you hear a line,then try to repeat it immediately). It's a good exercise for developing your ear to hands coordination, rather than eye to hands coordination. However that's only half of what's required. You are still trying to play something that's coming from you, and not just a rote 1950s riff. That goes back to whether you can sing a creative line then transfer it to your instrument.
There is no easy (pay money and get instant results) path to true improvisation. It takes years to develop the ability to play what you would sing, and (to be honest) not everybody can sing/create music in their heads! For those who have no musical ideas of their own and can't hear musical ideas, the only avenue may be what's commonly taught as a visual means of playing something that's not from you and definitely not creative.. but you're playing something that may satisfy you.
Know what you want, and better still have some idea of what your creative abilities may be! Way too many who have "talent" are taken down the academic (visual) path and wind up playing an archaic style of jazz (maybe even fluently!), but have no future playing that style of music and have spent years just practicing in that single vein. You are (or become) what you practice! Make wise decisions and don't be led by promises of instant anything, or going in a direction that is a dead end because that's where others have gone.