I bet you are going to have a hard time getting a good answer; if someone bought one, they likely didn't buy the other.
I can't speak to the first edition, but I found the second a bit sloppy in parts - inconsistent use of terms, things like that. Also I found the content organized awkwardly. While I understand the motivation to make a separate cloud certification, it should really be rolled into the CISSP given the prevalence of the cloud in today's environments. Similarly, as much as someone might understand the cloud, we are still accessing these services via traditional systems and networks. The broader concepts - governance, risk, compliance - apply equally to the cloud and traditional environments.
