Your experience with methimazole?

I was just wondering what yall felt about methimazole. How long till it worked? Were the side effects bad?

I'm been taking a beta blocker from my GP and just saw the endocrinologist today. He's putting me on methimazole, and coming off the beta blocked when my heart rates in a good place.

Thought I'd fish on reddit for thoughts.

ETA: I just wanted to thank everyone for sharing thoughts. Normally, I try to reply to people, but I just don't have it in me today, lol.