Poor and immensely frustrating. No problems connecting to one device. But when attempting to set up Party mode with a 2nd Bose Color II Soundlink device it only rarely connects to the 2nd device. Checking the Bluetooth settings it shows 2 connected but the app fails to operate the 2nd. The screen constantly rolls and appears to be attempting to connect, but never gets there. Annoyingly some weeks back it workly slighly better and I was able to set up Party Mode and select the Stereo option?