The change log is pretty long and there are a couple of minor incompatibilities to take note of:
"Update esp_init_data_default.bin. Please use the newest esp_init_data_default.bin when burning."
"Modify the espconn pointer in the receive callback of UDP. Parameters remote_ip and remote_port in it are the remote IP and port set by espconn_create. If users want to obtain IP and ports of the current sender, please call espconn_get_connection_info to get relevant information."
Especially the first bullet means that an OTA update isn't going to get you all benefits . Maybe someone can diff the old and new esp_init_data_default.bin so we can add the change to firmware?
Oh, almost forgot to add: there is now a force-sleep API, so no more guessing why the SDK doesn't power down the RF and such!
Update: docs at http://bbs.espressif.com/viewtopic.php?f=51&t=1024 and the SDK User Guide suggests on page 24 that the flash esp_init_data_default.bin change is most likely by 114 to determine whether RF calibration happens at boot time.