Besides the fact that I think they have a pushy, arrogant sales team, the overall value for what you are getting is not there.
I went in to look at mattresses and shop to see what options I had as I have just relocated to Charlotte and was in desperate need of a bed. I was greeted by someone who immediately started asking me questions and pushing me towards the highest price mattresses in the store. After making a remark that I couldn't justify spending $5K on a mattress the sales associate made a rude remark back to me with an arrogant tone as to how I could put a price on my sleep quality, somewhere I spent at least 6-8 hours a day.
Fortunately I did find a mattress at another store a few blocks away and am sleeping comfortably. They didn't pressure me to look at their most expensive models or make derogatory comments when I mentioned I didn't want to spend a lot of money on a mattress.