Zen Mattress On SALE $399 (Regular: $1700)

I am looking for a good mattress, Queen Size and I come across to Group and found that they have the Zen Mattress on sale. I am wondering if everyone has experiences with Zen mattress. I am looking forward to hear from you guys

http://www.groupon.com/deals/zen-bedrooms-4-ottawa-1

I am very tempting for this one? If not what is good one with my limited budget for a Queen Size Mattress (Around $400-600)

Thank you so much for your time guys