I am now running 15.03, and it seems pretty solid.
I have Kwikset Zigbee Locks (5), OmniStat2 RC2000, HAI Control Module, GE Light Bulbs, Smartenit Control Modules, Smartenit Repeater.
ZIM versions have had lots of bugs, including the ZIM clock not running, status not updating correctly, especially locks, and some devices, especially non-HAI devices not pairing correctly. the only problem i have with 15.03 is some non-HAI devices not pairing, but these devices did pair with 14.2X I can live with that, and status seems quite accurate, which is important, especially with locks.