Everything has been said, but I add: no way to set the pace 'digitally', only to walk and feeling - so no metronome function

UTILIZATION

Easy, but only intuitive (see above).
But I think the use without the 'tap tempo' is almost impossible, it must initiate and follow on pain of not being understood by the machine

SOUND QUALITY

For me correct, I see no difference with the original

OVERALL OPINION

I bought it secondhand because I was tired of playing alone. Since I'm in a band, it allows me to repeat my solos, test passages, etc. .... it really helps me to work and grow outside the repeats.
And above all, it's a huge help to compose.
Positive: it's really turned 'Guitarist', so no brainer (that guitarists have very small), everything is done to the foot.
But I realize the limitations: no metronome 'calibrated', it is almost impossible to caller correctly on a drum whose exterior would be given the tempo (which would still be easier: we put the 2-120 beeps and go!). In addition, without the use Tap Tempo is very uncertain, and with, impossible to caller on a pace that is already running (well, me, I really do not happen.
As discussed below, it also seems that my corny is not very accurate and slow down the pace over time.
I paid 150 zeuros (in its box), I will not pay more, but for the price I am not disappointed.