Excellent

I started learning Chinese with That's Mandarin in January 2023, and my experience so far has been great. I didn't have much expectation as I am not good at learning languages but my teacher is amazing, she is full of energy and joyful and it really helps.
They have a web-app you can use to review all your lessons and it provides writing/listening exercises, I find it quite useful at it allows me to study during my commute time and you don't have to carry books.
I didn't try other schools so I can't really compare but overall I believe That's Mandarin provide a wonderful experience for learning Chinese.