This is fine as long as we're talking about unique content that your visitors are after.
If I'm looking for a "handmade red widget" and I find your page www.example.com/widgets/handmade/red.html and it's got all the information I need, then good for you - I'll buy your product.
On the other hand, there are countless sites out there who are taking someone else's "feed" and generating pages this way - often without any unique content at all - and from the visitor's point of view, this stinks.
I was using Google and Froogle yesterday, looking for a 'small widget'. It seems that there's only one supplier of 'small widgets' where I am - but guess what, they run an affiliate program :-) So there were hundreds of matches. Sadly they were all for the same product. With the same price... and identical content on the product pages.
How is this a good experience for the visitor?
I gave up searching for my 'small widget' online and decided to try a local bricks-and-mortar store instead.