Machines like that are good for applying light products that don't need to be worked in heavily. Things like liquid wax and glazes (ie, Step 2 in those 3 step systems). They should allow you to get an even, very thin coat.
The only problem with them is that they don't have a lot of power or flexibility. They tend to bog down if you try to do any heavy work with them, and you're limited to one speed and the pads they give you (hope the terry bonnet is safe...).
So if you want to rub out defects with polishes and compounds I don't think this would be a good choice. You're better off doing it by hand, or getting something better (but much more expensive of course). If you want it to help you apply wax a little bit better, then okay.
My personal tilt though, is that liquid waxes and glaze aren't all that hard to apply by hand anyway, and I prefer pastes if I have a choice.