Pros
Great place to learn, but other schools are better honestly
Cons
0 work-life balance
Be careful who you decide to work for - an older professor will kick you out without a second thought if you aren't performing precisely to their standards, even if you're new, and many treat their students cruelly and unfairly. Some seem to weirdly relish bullying their students and post-docs for not knowing/ understanding a topic, messing up a reaction, etc. It's toxic and does not foster a constructive learning environment.
Most research professors are out of touch and expect way too much from their students. Most expect students to put in 80hr work weeks. Because professors are tenured the university/ department does little to help students.
If you decide to leave a group and try to join a different group - good luck. Professors view these students with contempt and will not make any effort to hear you out.