zpool list should show more detailed pool information
Historically the only way to see the usage of individual top-level devices within a pool was to run 'zpool iostat -v'. With the integration of 'PSARC 2008/353 zpool autoexpand property' ZFS could grow individual devices and expand top-level vdevs. Unfortunately it was not easy to determine if a LUN had expanded nor how it would impact ZFS top-level vdevs.
ZFS needs a way to display the expandable space of the pool as well as more detailed information for each device within the pool. Introducing a verbose option to 'zpool list' should accomplish this task.