- their API and code is a carbon copy of react-admin
- most features are half finished
- their benchmark is laughable if you look at the details
- they raised 1M$ and only sell mugs - watch out for the moment investor ask for they money back ("everything is free" isn't a good sign IMHO)
- they use the money to buy followers on social networks with contests
On the other hand, react-admin is mature (5+ years, ~4000 closed issues, huge unit test coverage and documentation), has passed breakeven point, and powers 3,000 new applications each month. It's published and supported by marmelab, a 10-year old company that has more than 70,000 stars across many projects on Github, and with very strong values (https://marmelab.com/en/values).
Prefer the original ;)