Review (5/5): Better battery means a better value in the long run.
Vendors of electric toothbrushes follow the razor-blade business: most of their profits come from the replacement brush heads. Low-end Oral-B brushes can be had for under $20, but paying a little more for an upscale model still makes sense because it comes with a stronger battery that lasts longer and cleans faster. In the long run, it represents a better value, particularly if the user is impatient (e.g. a young kid).