The thing that catches people out with wall lamps is the electrical question, nobody thinks about it until the lamp is sitting in a box and there's no outlet anywhere near where it needs to go. Hardwired sconces need a box in the wall and often an electrician, plug in versions need a cord you're willing to look at every day, and the two get mixed up on product pages more than they should. Even with that hassle, a pair of wall lamps can do more for a room than another floor lamp ever will, because the light comes from up and out instead of pooling at ankle height.
Measuring matters more here than with almost any other lamp. The classic mistake is hanging them too low, like bedside table height, when they actually want to sit around 60 to 66 inches off the floor so the light clears your eyeline when you're sitting or lying down. For a bedroom, measure from the mattress top, not the floor, and leave at least 20 inches between the lamp and the edge of the bed so you're not ducking under it to find a book. For a hallway or stairwell, space them out evenly rather than guessing, and hold a paper template up before you commit to drilling, because a lamp that looks small in a listing photo can look enormous eight feet up on a narrow wall. As for finish, matte black and aged brass read as more substantial in person than chrome, which can look a little thin and cold once it's actually mounted.
A well made wall lamp has weight to it, even the small ones. Pick it up and the metal arm shouldn't flex, the joints where the arm swivels should move with some resistance, not rattle loose after a month. Cheap versions use a thin pot metal that dents if you bump it with a vacuum, and the paint or plating wears through at the joint within a year. Look for a proper swing arm with a visible hinge if you want to read in bed, and check the shade attachment, a lamp with a flimsy harp will tilt every time you adjust it. Glass shades diffuse better than fabric but show fingerprints, fabric shades soften the light beautifully but yellow with cigarette smoke or kitchen grease faster than you'd expect.
Skip wall lamps entirely if you're in a rental that won't let you drill, or if you need serious reading light rather than ambience, they're mood lighting first and task lighting a distant second. The one mistake to avoid is hanging them before you've sat or lain in the exact spot where you'll actually use them.