I went to a Whole Foods one time. Didn’t like it at all. Overpriced, off-brand products in a cramped store with narrow aisles.
The ones here in the Houston area are very modern and spacious. However, they are definitely over-priced. I do not see them as competition for regular grocers for that reason. It would be like saying Lexus is competition against Toyota Corollas. Also, they don't carry lots of things a person needs on a daily basis. One would have to shop at another store to get the rest of the things one needs. They do not carry the most recognizable brand names we are all familiar with.
One good thing I will say for them is that they came through after Hurricane Ike hit this area in 2008. Most of the grocery stores in my area were out of pretty much everything. Whole Foods was 100% in stock.
Sounds like the only one I have been in, Jackson, WY. The last time I was passing through, I didn’t see it. Maybe they went under. The store we like which isn’t available where we live, is WINCO.