Small units get treated like an afterthought, the thing you buy to fill a gap rather than a piece you actually chose, and I get why. But I landed on them being some of the hardest working furniture in a small space, because a narrow cabinet that fits an awkward corner and actually looks good there is worth more than a big statement piece you had to compromise the room to fit around.
A cheap small unit tells on itself fast. The veneer lifts at the corners within a year, the back panel is thin enough to flex when you push a book against it, and the drawer runners start sticking by month eight. A well made one ages the other way, the wood gets a little richer, the hardware stays tight, and you can tighten a hinge yourself instead of replacing the whole thing. Wipe it down, keep it out of direct sun if it is a stained wood that can fade unevenly, and check the levelers every so often if your floors aren't perfectly flat, which, in most real houses, they are not. When it arrives, open every drawer and door before the delivery person leaves. Check the back is solid, not stapled cardboard. Run your hand along the underside of the top for rough edges. Small units get knocked and bumped more than big furniture because they live in tight spots, hallways, the end of a sofa, so the finish needs to actually hold up to contact, not just look good in a photo.
These work best in the rooms where space is already spoken for, a studio apartment, a narrow entryway, a rental with a weird nook nobody designed for. They are quietly brilliant in bedrooms as a nightstand substitute with actual storage, and in living rooms where you need a surface without committing to a full console. Winter makes them earn their place even more, when everyone is layering coats and scarves and you need somewhere for them that is not the floor.
Color is where a small unit either disappears or does something. A plain wood or white one is fine, but a unit in a deep color, forest green, a warm terracotta, even a glossy navy, turns a boring corner into the thing people actually notice. My mother has three beige small cabinets in her hallway and has never once been asked about them. Pair one with a single piece of art above it and a lamp that throws warm light, and it stops being storage and starts being a little moment in the room.
What it won't do is replace real storage for a family home. For one or two people in a tight space, it is close to perfect. For a house full of coats, shoes and sports gear, it is a nice extra, not the whole answer.