Shards of Earth hits everything I love about space opera. Great characters, a grand scale, interesting technology, aliens that are actually alien, Big Mysterious Things, and general fast-paced awesomeness.
The Architects are moon-sized aliens that, inexplicably and unstoppably, tear inhabited planets apart and turn them into flower-like structures, killing everything on the planet. This has already happened to Earth. However, a ragtag group of scavengers stumbles upon a floating, wrecked spaceship that may have an answer to stopping the Architects. If they can survive long enough to attempt to stop them, that is.
Recommendation: Read it, if space opera is your thing. Author Adrian Tchaikovsky is fantastic.