I like SmashWords, and have read a few books from there. The best thing about SmashWords is that pretty much anybody who wants to can publish their books there. Unfortunately, the
worst thing about SmashWords is that anybody who wants to can publish their books there.
I tend to look for authors who offer both free and priced books. This way, I can sample their work before making a commitment to purchase something else from them. It has definitely helped in weeding out a lot of the "bad eggs" out of a bunch and allowing the golden ones to shine more brightly.
The way I see it, SmashWords is a lot like the iTunes "App Store," in that any indie can create something and sell it there. This sadly means that there will undoubtedly be
far more "rotten apples" than "golden delicious" types of content.
On the bright side, since by their very definition, "indies" are not held back by publishers who have their own agenda and shareholders to pay, which allows indies to experiment in ways most other developers don't have the luxury of doing. This creates some very unique and interesting content. It is, however, buried deep under the slush of 'crapps', making it hard to discern if one is making a good purchase or not.
The same can be said of SmashWords. It's an indie's paradise. But because of its open nature, one must work harder to stand out from the rest of the crowd.