A good metal light fixture has a certain heft to it before you even plug it in. You pick up the shade and it doesn't feel like it might dent if you look at it wrong. The switch has a solid click instead of a cheap little rattle, and when the light's on, metal does something nice to it, either throwing a warm wash if it's brass or bronze, or a cooler, sharper glow if it's black or chrome. It sits there looking like it'll outlast the lease, which, with metal, it usually does.
Getting the size right is where most people trip up, myself included. I once hung a pendant over a kitchen table that looked perfectly reasonable in the box and then turned into this tiny, apologetic dot of light once it was up, swinging over a six foot table like it had wandered in from a dollhouse. The rule that actually works is to measure the space it needs to fill, not just eyeball it against the ceiling height. For a table or island, you want the fixture roughly a third to half the width of what's underneath it. For floor and table lamps, check the shade height against where you'll actually be sitting, because a shade that blinds you at eye level the second you sit on the couch is a mistake you'll be annoyed about every single night. And always check the drop length against your ceiling height, not the showroom's, because nine foot ceilings and eight foot ceilings want very different hanging heights.
Metal plays well with almost everything else in a room because it doesn't compete the way patterned fabric or busy wood grain can. It sits easily against wood furniture, especially anything with some age or grain to it, and it looks good next to soft things, linen curtains, a worn rug, a nubby throw, because the contrast does the work. Where it struggles a little is next to a lot of other shiny, hard surfaces, chrome taps, glass tables, glossy cabinets, all together it starts to feel cold rather than sharp. One warm metal fixture against mostly soft, textured surroundings is the combination that keeps working.
These do well almost anywhere, honestly, but they particularly suit rooms with some age or character already, exposed brick, older moldings, a worn wood floor, because metal doesn't try to compete with character, it just sits alongside it. They're also a good choice for renters, since a well made metal fixture will survive several apartments and several more opinions about what the next place should look like. The detail that always gets me is the sound a metal lamp makes when you set a glass down near its base. A quiet, solid little clink instead of nothing at all.