Experimental software which does not sometimes work properly (no positive effect to EEG).
Software can change measurable brainwaves a bit but how it affects to brain performance is unknown.
Sometimes with certain "should-work" settings you get "lack of focus" effect that disappears after one night of good sleep.
Requires fast CPU and running times even for small effects are long (hours). Typically, you need about 500-1000 iterations before some useful results. If you calculate an iteration in 30 seconds, it means 4-8.3 hours of stimulation.
Command-line software is hard to use.