Steins;Gate was an amazing anime that was full of twists and turns and a very heartwrenching story on sacrifice and moving on. Steins Gate 0 is more of that, but worse in many ways.
Most of the plot twists were really predictable especially since the anime beats you in the head with its 'hints' and assumes you wouldn't get it, but I knew where a lot of plot points were going just a few episodes in. A lot of the episodes feel disconnected and some of them are just repeating the exact same points: Okabe is depressed, Mayuri wants him to be happy, the other guys want to try and fix the timeline. It's the same few cliches done for a long time. The action scenes are also horrible, but thankfully they don't take much screen time.
That said, steins;gate 0 *is* a good sequel to the first, but keep your expectations low. Some scenes were really powerful, and in the end it feels like it wraps up the series in a fairly satisfying way. I'd give this a 6.5/10.