I moved nearly all my domains (50+) to Cloudflare a few years back, saving me something like 200 quid a year from my old provider. Only domains outside cloudflare are my .ie domains, which are currently not supported and I think one or 2 others that haven't been supported yet. Handy to have the rest of the cloudflare services on there too.

Great but only so long as you want to use their nameservers. I had a domain with them that I wanted to use with AWS Route 53 nameservers which I was unable to - then I had to wait the standard ~60 days before I could transfer it out which caused a headache in the meantime.