To be honest, I don't like anything about Cassandra. Beginning with the naming: back when I was trying to learn about Cassandra, I couldn't get past the obscure and bizarre naming (super-columns?). When I dealt with systems using it, I never quite understood how you can keep saying that "the later timestamp wins" and speak of consistency with a straight face: in a distributed system, there is no such thing as a "later timestamp". Or speak of transactions which aren't really transactions at all.

Then I read the Jepsen reports about Cassandra. Yes, Cassandra has made progress since then, but still.

I think of Cassandra as an outdated piece of technology at this point: we can (and do) build better distributed databases today, with better consistency guarantees, and proper transactions in case of FoundationDB. Cassandra was designed for a specific use case and then outgrew its initial design, because there was nothing else at the time. But I see no reason to stick with it any longer.

Even now when you need massive multi-region scalability there is little to choose from — if you want it to be open-source, there's pretty much only FoundationDB left.