I've tried at least 10 different battery-powered Bluetooth speakers, and the walnut cased Grain Audio PWS is by far my favorite. At $(removed), it's also the most expensive. But I think it's worth it, especially since I use it almost every day.
I admire the simple design and the wood case. The sound is rich and doesn't have that overcompressed, processed sound that I hear in cheaper speakers. At 7 x 3 x 2.5 inches, it's quite bit bigger than the well-known $(removed) Jambox, which measures 6 x 2.25 x 1.5. The sound quality of the Grain is noticeably deeper than the Jambox, which sounds downright tinny compared to the Grain.
I still use my Jambox when I'm doing stuff outside or traveling, because I don't want the Grain to get damaged. (Plus, the Jambox is a lot lighter and more pocketable than the Grain.) But for home use, I go to the Grain.