I bought one of these mattresses 2/2008.  [...], I gave one to a friend who uses it as his bed and has it on an old set of box springs.  He loves it and has no problems with it!  Mine is used on a futon which serves as my couch.  Three of the strings have come out and in the last month, the foam covering the springs along the edge where I sit has fallen down leaving the springs exposed.  I rotate it about every 6 months, and this is the first place to do this.  It's a 3 year old mattress under a 10 yr warranty, so I'm hoping I can resolve the issue.  [...], this mattress is definitely worth the $ because of how comfortable and durably they both have been.