Pretty cool a new back I see how it works it's a good idea though I won't drop cash for it. Free stickers are nice to go with it though. Lot of different stickers out there on amazon now for your go plus for those who haven't looked. You can get lapras snorlax, umbreon, espeon, haunter, blastoise and more even real wood grain look. Simple "pokemon go plus" search in amazon brings em up.
Wood Grain for Mystic, Valor, and Instinct
Umbreon See below others like it by this company for more choices as described above.
There's even a leather zipped protective holder case