I just picked up a Sonos Play 3 and Bridge and I have been having some trouble with the album art thumbnails. In the Artist and Album lists where it shows a thumbnail of the album cover, some of my album covers don't show up. But if I play the album I see the cover in the "Now Playing" screen. This is on my iPhone 5. The thumbnails show up fine in my Sonos player on my iMac.
Also, the little logos for Pandora, Spotify, Slacker,iHeartRadio, and other internet radio/streaming services don't appear on my iPhone 5. It just shows the default image (a treble clef). However, these logos show up fine in my Sonos player on my iMac.