Serta Perfect Day iSeries Mattress feedback on Amazon has mostly positive reviews, as of 2015. iSeries reviews on ConsumerAffairs are mostly negative, with 69 people giving one star out of five. Sleep Like The Dead compared the iSeries with other mattresses and gave it mostly between B+ and C- ratings.
The Amazon positive reviews point out the high comfort level and back pain alleviation properties, while the negative reviews report a high occurrence of sagging and the company's refusal to change it until the sagging reaches the depth stipulated in the warranty. The ConsumerAffairs reviews also point out the sagging issues that occur after a few months to a few years. The iSeries review done by Sleep Like The Dead reports availability and firmness as strong points.