Superman: The Black Ring, volume 1 collects Action Comics #890-895, all originally published in 2010. Continuity-wise, the story takes place after Blackest Night and the Superman: New Krypton saga, but overall it is fairly self-contained (in fact, it seems to ignore the events of New Krypton altogether). Like other recent DC hardcovers, the production quality is barely passable: medium-gloss paper, unfinished boards, and a sloppy application of glue (my copy makes a funny noise whenever opened--indicating insufficient glue along the interior cover). DC has also continued their practice of omitting issue numbers, which will annoy some serious collectors.
Story-wise, The Black Ring features a post-Blackest-Night Lex Luthor as the central protagonist, accompanied by an android Lois Lane. Together, they hunt the globe for residual "black ring" energy, in the process encountering Mister Mind, Gorilla Grodd, Vandal Savage, and even Death (from Neil Gaiman's Sandman). Deathstroke also makes a minor appearance. Paul Cornell's story is imaginative, compelling, and darkly funny--the freshest plot to grace a Superman book since Geoff Johns's Superman: Brainiac. The art, provided primarily by Pete Woods, fits the story well. His Luthor--seemingly modeled after Michael Rosenbaum's Luthor for Smallville--is a much more expressive and human-seeming Lex than is typical.
Ultimately, Superman: Black Ring is a must read for Superman fans and casual readers alike. If only DC could fix the quality of their hardbacks, this would be a perfect buy.