Funnily enough I was looking into this the other day. I have a birthday coming up and I never know what to ask for but was thinking of either a face toner or a permanent hair remover (but not the no-no which seems to have a monopoly on qvc these days and rubbish reviews). Oh the joys of getting older.
Anyway, I haven't found too many rave reviews of the slendertone gadget. I think people who invest that amount of cash really want to see results and scrutinise themselves for any small improvements so it may work to some small extent. They say that positioning the pads isn't easy and that the back of the headset is prone to snap, rendering the unit useless.
All that said, if you're in the market for something like this then qvc is just the place to buy it from and I might well give it a go.