Just as good as ER
Both shows are great, both are different, Code Black will always be compared to ER due to the main topic, but don't worry about that. What is strange is that nobody is comparing Grey's Anatomy to ER which are both similar because they focus a lot on the characters personal lives.
Code Black is obviously doing well with American audiences, good for them! I hope the show lasts for years, it probably will, the performances are decent and it's an informative TV Show, you can learn a lot of things about hospitals, operations and surgeries, the hospital lingo is always a good thing to learn in general.