The X series is known for being a little rough out of the gate, so when X Rebirth came out with some major bugs, no one was really surprised. Egosoft has been releasing a lot of patches, but the game is still borderline unplayable. It's more than just a few weird glitches or flaws -- nothing in X Rebirth feels ready to be played.
Beyond just being glitchy, the core gameplay mechanics are flawed. The menu systems are hard to navigate, it's hard to know what you should be doing or what you can do, doing a simple task is an exercise in patience, and I always felt like I was fighting the game's mechanics to get anything done.
There is some good stuff in here, but anything worth playing in X Rebirth was done better by X3: Terran Conflict. X Rebirth was supposed to be a new starting point for the series, a game to bring in new players while keeping the old spirit alive. Instead, we have a game that scares away newcomers and upsets fans of the series.