I had one like this years ago and loved it.  I hated it when it went "belly-up".  I have since had other brands and do not like them nearly as much as this brand.  I like the idea of having the additional battery so you can change it if you need to and I it is already charged and ready to go.  Have used it on both carpeting and on bare floors and was surprised at the amount of dog hair and general dust and debris it picked up after using it only twice.  I really like this product.  It is much more stable feeling than the one I was using prior to getting this.