i used the goof off method on my dad's e39 when he first got it in '01.
to protect other parts of the visor, take some masking tape and make a border around the sticker. take goof off, and apply it onto a cotton ball. take the cotton ball and dab the sticker all over. you should start to see the sticker wrinkling. at this point, start at a corner, and slowly start peeling the sticker off. there might be some adhesive left over, and i'd use something less powerful to clean that up like goo gone.
on my dad's e39, it left a slight shadow.
i have yet to do this on the e90.
also, i would only do this if you have vinyl visors.