I used to use one. If you get one, be sure to get the one with the finer needle and smaller tacks (Dennison is a good brand). Once I tried spray basting, I never went back to the tack gun; however, I prefered the tack gun to pinning and thread basting.
The biggest problem I had using the tacks was if I laid the quilt sandwich out on a table; in this case, you need a way to lift the quilt up a section at a time so the tack doesn't hit the table. Solved that problem by using an old-fashioned 2x4 frame with clamps.
Had to remove the tacks in small sections at a time while machine quilting or hand quilting.
Spray basting is so much easier.