Farmhouse sinks are big. Huge. (Huge in the sense that they're very trendy, and also huge in the sense that they're very large.) They figure in a lot of very stylish kitchens, and, if you're remodeling, chances are good that you're considering one for your kitchen, too. But farmhouse (or apron front) sinks do have one drawback that's worth keeping in mind.
Because these sinks are so large, and because they protrude in front of the cabinets (that so-called apron front that also gives them their distinctive look), they require a special countertop cut. Depending on the kind of farmhouse sink you're dealing with, the surrounding countertop will either have to be cut so that there's just a tiny sliver of countertop behind the sink, or so the surface is interrupted completely by the sink (as is the case with many top-mount farmhouse sinks).
All this is fine, and helps to give these sinks their unique look. But it also means that if, for whatever reason, you tire of your farmhouse sink, you can only ever replace it with another farmhouse-style sink, unless you want to buy a new countertop entirely, which is a pretty expensive proposition.
Apron front sinks also require a unique kind of sink cabinet. If you take a look at your average sink cabinet, you'll notice that it has doors below, and above the doors, in front of the sink, what looks like a drawer (to blend in with the rest of the kitchen cabinets) but isn't. In order to accommodate a farmhouse sink, you'll either need to buy a sink cabinet that is designed specifically for one, or have your contractor (or yourself) cut through that fake drawer bit at the top to accommodate the apron front. It's not a big loss in terms of storage, but it does mean that your sink cabinet is now unsuitable for any other kind of sink.
So farmhouse sinks, besides just being big, are a big investment — you can't get tired of one and switch it out in a few years, without changing basically your entire kitchen. It's hard to say if these are a fad, or something that will still be catching eyes in kitchens years from now—but we can say, if you're going to install a farmhouse sink, make sure you're in it for the long haul.