My mattress was old, and it was a cheap one to begin with, so my back was really starting to bother me on a daily basis.  I didn't have the money to buy a new mattress, so I decided to give this topper a try, even though I didn't think I would really like memory foam.  I've only slept on it for 4 nights, but my back does not ache in the morning the way it did.  Memory foam is different, and when I initially get into bed it still feels odd to me, but overall, it is very comfortable to sleep on.  

Pros: Great value and can save you a lot of money if you can hold off on buying a new bed.
Cons: Not sure how long it will last; it takes a bit to get used to it.