is this product good to cut holes in drywall?

A "Roto-Zip" type tool works much better.

I'm sure it would cut holes in drywall but it isn't what I'd consider a drywall tool. It is designed to do lighter finer work... last use by me was to inlet a new stock for a rifle... tedious fine work that MUST fit perfectly. The tools are set up to cut smaller wholes than those for electric sockets and such. I usually cut drywall with a very sharp lock back knife. I also cut drywall with a tool similar to the PORTER-CABLE 3-Amp 3-Amp Oscillating Tool Kit. There make both hard wired and battery versions. I have and prefer the battery version. It will NOT cut through oak or 3/4 inch plywood but is great for making cuts in hard to reach places in material that is easier to cut.. On slightly heavier materials... I used mine extensively while remodeling my kitchen counter which is done in Italian tile. It does a good job of "worrying" off corners and edges that don't fit perfect. As said, I've also used it to cut... Drywall. It has penetration tools that will start cuts in light materials, easy to cut materials like drywall. Start in the MIDDLE of the knockout you need to keep the hole neat. IMHO its an affectation as I can do the same cuts with a high quality well sharpened knife or even a razor knife. Of course the knife will eventually make my hand and wrist sore and tired on a big project so I turn to the Oscillation Tool.

The Blue Hawk 130-piece Rotary Kit is an excellent choice for cutting percision holes in drywall.