How useful is laser treatment for plantar warts?

It can be: There are many different ways to treat warts. The laser is a useful (and expensive) tool to treat them, but i cannot say that using one works significantly better than other measures. See a podiatrist or dermatologist to discuss your treatment options.

Can work.: There are lots of treatments for warts, and all can work, including laser therapy. Other options your doctor might offer include cryotherapy (freezing the wart), electrocautery (burning the wart), or several different topical chemical treatments. If the treatment is typically uncomfortable, your doctor can numb the area before proceeding.