Has anything changed recently? Looks like PPC is rallying. Is it still centralized via checkpoints?
The big change is that development is no longer centralized on Sunny King, although that change already happened last year. They concentrate now on the Peerassets platform to make "tokens" and "DAOs" possible on the PPC blockchain.
The checkpoints still exist, but they are not longer enforced by the protocol. People can "turn them off" in the client, and use them if there is a fork event (to decide which chain is the best one). So they are now a bit closer to what Weak subjectivity* is about ...
*
Weak subjectivity refers to the fact that in PoS blockchains there is no "objective truth" possible, because in theory everybody could "fake" his version of the blockchain via forking and double spending (although it's not trivial). But in the case there's ambiguity nodes can voluntarily decide to
subjectively trust some sources more than others (in this case, the "checkpoint node"), and then the system should work fine.