The UI is much nicer than gerrit (or at least the gerrit UI I knew from 5-6 years ago not sure if they have changed). It’s more “GitHub”-y. It’s a bit confusing at first but once you get into it it’s pretty damn powerful.
Side note, I honestly seriously think we need much better tooling than just these 2 for code reviews.
I'm building a much better code review for tool for GitHub, check out https://codeapprove.com
It combines concepts from GitHub, Gerrit, and other good review tools out there to make it easy and fast to reach consensus (which is what it's all about).
If you want to hear more you can email me at sam at habosa dot com
Gerrit has gotten a new UI in the last few years as far as i know. I wouldnt nesecarily describe it as pretty, but its my personal favourite review system
Side note, I honestly seriously think we need much better tooling than just these 2 for code reviews.