A cabinet with a shelf has a reputation for being the furniture equivalent of a junk drawer that got lucky and grew legs. Somewhere to stack what doesn't have another home. I used to think that too, until I actually lived with one, and now I think it's one of the more useful pieces you can own, because that open shelf stops the whole thing from feeling like a closed box shoved against a wall.
In an ordinary room it sits well doing double duty, which is really the point of it. Put one in a living room and it holds the television's mess of cables and boxes behind closed doors while the shelf takes a stack of books, a lamp, something with a bit of height. In a dining room it works as the place that holds linens and serving dishes inside while the shelf carries whatever you're using that week, a bowl of fruit, a stack of plates waiting to go on the table. In an entryway it catches shoes and bags out of sight while the shelf takes keys and mail, which stops that pile from colonizing the kitchen counter. If you've got none of these and you're buying your first one, start plain and mid height, somewhere around waist level, in a wood tone or a simple painted finish that matches what you already have. Avoid anything too tall or too narrow on your first try, since those tend to tip the room off balance before you even know what else you need around it.
Where the well made ones separate from the sad ones is mostly in what you can't see at first glance. Pick it up, or at least try to shift it, and a solid one feels planted rather than hollow. Look at the back panel, since a thin stapled sheet of fiberboard back there is a tell that the rest was built to match. Drawers and doors should sit flush and close with a bit of weight behind them, not rattle or hang slightly open on their own. The shelf edge itself should be finished the same as the rest, not a bare unsealed strip that will mark the first time something wet sits on it. A cheap one usually gives itself away within a year, doors sagging, veneer lifting at the corner, the whole thing looking tired long before it should.
Where it doesn't belong is anywhere already tight on floor space, since the open shelf needs a little visual room to breathe or it just reads as more clutter stacked on more clutter.
Wipe the shelf down regularly, since open shelves collect dust faster than anything with a door on it.