I've bought a couple of mattress sets from them and have been satisfied. They provide decent value and a good selection. No issues, so don't know about service after the sale. Costco probably has better prices if they have what you want, but their selection is limited.
i've bought 2 mattresses from them and been extremely happy with both. i shopped around a lot before buying a mattress and wasn't concerned about price b/c it's an important piece. denver is well priced and it's far and away the best mattress i've ever had. bought my first in 02. left it in nyc when i moved back to austin and bought my second in 06. i recommend them to everyone and will buy my next mattress there.
TexAnne-- Come to the next Texas game, bring a truck, and go to a place here in Austin called ATX Mattress. They have closeouts, way cheaper than anywhere else-- and they'll deal if you hand them cash. We bought a Sealy Posturepedic pillowtop king for 700 back in Nov. They don't always have the best selection b/c it's "closeout", but they have damn good deals. The Link