Mostly sheet, but lots of angle and tubing too. It's chewed through some aluminum plate (1/4"-1/2") a time or two as well. Even some 1" tooling plate. I used to keep it in my box at work, but took it home as I always needed it more there. Nothing worse than needing a tool at home you have at work, or the other way around.
If I didn't have a horizontal bandsaw I'd still use it for 45* mitering of angle (ex 2x2x1/8"). Really quick, and imo way better than a portaband, or angle grinder. Super easy to follow layout lines, and get a nice fitting joint.
Variable speed is what makes it so versatile. And good blades are necessary.
For a good while it was my only metal cutting tool besides a recip saw, and angle grinder at home. I don't use it much anymore because I have better options, but I should bust it out more as it IS pretty handy to have around. Portaband tends to be the go to because it hangs on a hook next to the vise. Even if it isn't always the best tool for the job.
EDIT: one of the best reasons I liked it so much is that it was quiet. I hate air tools, and loud angle grinders etc. I'd rather take a bit longer, than listen to that racket. It's also pretty clean too. Chips just fall to the floor, and don't get flung around the shop all over the place. I used a wax stick lubricant on the blades too.