They work good! In fact, we coincidentally just ordered a larger on this morning.
They'll save more than they cost just in transfer
paper the first year you have one.
We've owned the two we have for about 10 years. We still use application tape for some jobs (the frames won't work for putting vinyl on vehicles for example) but use far, far less tape than we use to.
Takes only a few minutes to get the hang of them. No shop should be without one, in my opinion.
The one thing you'll have to experiment with is the three different "tapes".
There's low tack, medium and high tack.
Depends on what surfaces you're going to be using them on...and the humidity of your region.
We use the low tack.
Good luck and have fun! They're much faster than anything else.