My wife and I had recently upgraded to a king-size bed and purchased a foam (but not memory foam) mattress. The mattress was too firm for me, but she wasn't having problems sleeping. After I convinced her to give this a try, we both love it. Plenty of support when sleeping on your side or back, and just a joy to lay down on at night. I end up sleeping on my stomach a lot, and I do not wake up with any of the pain I used to have on the mattress alone. The cover adds a nice quilted padding and fits perfectly over the topper. I don't think the cover is 1.5" thick, but it's thick enough to notice, and the whole thing adds a good 3.5" to the bed height. We have a low platform bed on a slatted base, and this raised the top of the bed to just the right height. Have not had any overheating issues, even with two comforters and a sheet at night.
I would definitely buy this again.