Bed Boost really worked great for the depression in my 8-year-old mattress. Perhaps my bed's sagging wasn't that bad because I didn't have to inflate the Bed Boost all that much and it was very easy to over-inflate. It smoothed out the sag and it became 100% better. Besides, I didn't have that much to lose since I found one at Ross for $2.99 less 10%.
Bottom Line: Yes, I would recommend this to a friend