Diamond Dogs marks the end of an era. Before he cut this record, Bowie fired the Spiders from Mars and dropped his Ziggy Stardust persona. Unsurprisingly, Diamond Dogs sounds like a transitional album. As such, it's significantly less stable than its predecessors.
There are definitely some tracks worth hearing on Diamond Dogs. Most notably, the title track, "Sweet Thing," and "Rebel Rebel," are worthy of Bowie's earlier work. Unfortunately, there are a few disappointments on this album as well. I found "1984" tedious and "Chant of the Ever Circling Skeletal Family" odd for oddness' sake. Although it suffers from unevenness, Diamond Dogs is still worth owning, provided you already own Hunky Dory and Ziggy Stardust.