The answers depend of the regions and countries. Therew strong differences which are still evident regarding prepardness. WEhile in some countries the process has been very positive since months ago, there are still countries discussing about El Niño existence which meand limited prepardness and expected higher impacts.
However, there are many positive examples about how the climate information trigered policy decisions and concrete actions. One of the indicators of course will be the comparison of past and curent impacts (human losses, social impacts, cost of losses). Other indicators could be the impacts per sector and the comparison with 97-98, which is the most appropiate base line.
El Niño is expected to peak between November 2015 and January 2016. After this the declination phase is slow and the influence will remain specially in the Tropical Eastern Pacific till June 2016. We are facin an STRONG El Niño.
In addition to the previous indicators, we can add, the number of people well informed before andd during the event. It seems to me that climate information chain to reach the last mile (small farmers, indigenous comunities, fishermen) is still the big challenge. However, great improvement has been evidenced in delivering information to Governmental authorities, policy makers, and representatives of sectors (big scale).