Any new exchange will always be good for crypto, especially one that already has an established user base and offers zero fees. It will be interesting however to see if they are one of those exchanges that claims to offer zero fees but that's because they make up all of their profit by offering very low exchange rates.
It wasn't exactly detailed how they would be making money from crypto. They make it work with stocks by selling order flow to exchanges and using idle money for investment
Now Robinhood advertise activly its exchance in order to make huge amounts of people use its services, luring 0% comission. And then their admins will gradually increase comissions, but it is only to my thinking.
They've actually had commission free stock trading for the past 5 years have have never wavered on their business model even as the company has grown to be worth over 1.3 billion dollars today. I don't see them ever adding commissions, but I think they'll add in more premium services and higher margin rates over time in order to increase their income.