I saw this product about a week ago while I was searching for ATS resume builders, I was tired of using MS word to create and maintain my resume. It was hectic and most of the time the templates were not that good. I searched for templates and ended up using Canva for a while, which was fine till I actually used it for applying for a job.
That website/company wasn't accepting it. I tried it again and finally found out that the reason. My resume was not ATS compatible, their ATS couldn't read it because all the information was all over the place. I searched for ATS friendly resume builders and found Rezi. I was hoping for a discount and I found it on Appsumo and bought the Lifetime subscription for $29 (their website sell it for $89).
Finaly created a resume with it and applied again; BOOM! to my surprise, the website filled most of the fields its own after reading the resume. - I think this is what an ATS ready does to a resume.

Things I like about them
1. Very structured resume builder that makes sure that you don't miss anything.
2. I always had trouble writing something, like a starting trouble where your mind goes blank. Their AI resume writer really helped me in this regard, I just had to enter my last position and it was like it read my mind, it started generating sentences based on that role.
3. Regular updates - They have updated the entire app with new technology 3 times already in the past year. $29 is a sweet deal for a lifetime of updates.
4. Rezi Score and Content analysis helps us to make a great resume - I got a score of 96 :)

What they could improve
1. I'd love to see more ATS friendly resume templates in the future, this can be hard as ATS read resumes from left to right, but I'd love some customizations like adding a different background.

TL;DR: If you are looking for a career at a good company, Rezi lifetime deal is worth the investment.