I bought this because it got rave reviews and I was no longer fitting comfortably in my clothes and was still trying to hide my pregnancy.  I ended up only using a few times.  It was summer, and I thought it showed too obviously under thinner summer clothing ( you could see that my pants were unbuttoned and that I had another "layer" on underneath, which to me defeated the purpose).  Maybe it would be more useful in the fall or winter.
Also, maybe its because I am short-waisted, but I could only get the band to lay flat if I stayed standing the whole time.  Once I sat down, it rolled down and bunched up, and I would have to readjust again when I stood up, which was very obvious.  Also, I never found the need to use this again in later pregnancy either.
I think this product may serve its purpose, and is a good backup to have, but it wasn't a must buy to me.