I think they look very nice although the front 2 teeth would look nicer if they were a little longer.The photo does not show the inconsistency of color you mention. There would be no way of changing that without removing the veneers and doing something different underneath or making them...
Today's veneers look better than ever so because your Mom's veneers are older, she may want to get a consultation on options that could look more natural.Not all dentists do veneers equally well so do some research on well-reviewed cosmetic dentists in your area.
Without all the information it's difficult to give an exact answer. However, it sounds as if the dentist was very quick to do porcelain veneers without doing the required tests, such as full mouth X-rays, periodontal exam, and a visit to a root canal specialist for an opinion about resorption....
