In e-commerce, I think it makes the most sense to use faceted
navigation when there's more than one criterion by which customers
are likely to evaluate products/services--which turns out to be most
of the time when you're dealing with a catalog of any size, IMO.
If you have a few items with only two facets, but the majority lend
themselves to multiple facets that are meaningful to customers, I
don't think that's a problem. But if your catalog consistently
supports only two facets (for example, brand and price), each with
only a handful of attributes, then faceting may be overkill. The key
to making the use of facets make sense, I think, is to find the right
It isn't a perfect technique for every situation. If your product
hierarchy is very granular, and you then apply faceted navigation on
top of it, you may wind up with something like this example from
This may not be inherently "wrong" or bad, but it does seem like a
lot of work to get to that one product (which is one of two products
in the Electronics > Batteries > General Purpose category). Faceting
isn't what's wrong with that example, but it's not adding much to
the experience either. And if I were shopping for batteries at Sam's
Club, the single facet used in that category--price--wouldn't be
helpful to me, because I shop for batteries by brand, which is a
facet that they didn't use.
In general, I'm a big fan of faceted classification both for
narrowing large search result sets and for informing navigation. But
it's not appropriate for every instance.