Thing works great! I've cut 16 gauge steel with it and had no problems, but I didn't cut too much at this thickness, the tool seemed to run out and the cutter would dull or damage with frequent use on 16 gauge. . It cuts through 18 ga like butter, haven't used it on anything thinner but should cut very well. It leaves a nice, burr-free cut edge, it's not totally smooth, but it can be neatened up quickly if you want it to be 100% smooth. It doesn't leave an edge for you to cut, which is pretty cool. The circle cutter is nice to have and works quite well, I'll probably make some modifications to mine to better mount it on the tool head. The only downside to cutting circles with an attachment is that you have to drill the entry hole for the cutting head in the center of the edge of your circle, so you end up with half an entry hole outside of the circle you are cutting. In general, the tool is excellent, it is much easier to cut sheet metal with it than with a grinder, jigsaw or saber saw. Cutting holes is easier and cleaner than with a hole saw. The smallest circle you can cut with the cutter is about 1.75 inches.