Can be good but.....
Gumtree is promoted as a free service to enable you to sell your unwanted goods. To an extent it is true, you can sell some items for free, but others to get any real exposure you need to upgrade to some of their paid enhanced listings. It is a little sneaky when you think E-bay is upfront about fees before you list and they have a much larger following. I would say give Gumtree a go within the free listings, and if no cigar consider other options before paying. Gumtree still might be the right place for your unwanted items.