Enough time has passed since the V5.1.0 production release to have some statistics with enough underlying data to be meaningful.
The following statistics are based on "sessions", not "users", so people who use CC more frequently are counted more often.
List vs Grid View
Reading Books
Looking at Book Details
Grouping
Sorting
Connection Type
Cloud Provider Usage
Library Size (CC full version only)
"Find Random Book" was used in 5% of the sessions, which is substantially more than I would have expected.