Decoin exchange is +14% in volume, it is shown us a good development, but the exchange score is too small to be top 20 in cmc in very less time, only 3.6, because I see that the top 20 are those who have an average exchange score above 6. It seems that they have a lot more thing to improve or develop.
Yes there is a lot of room for improvement. I have been requesting this on their telegram group too that they should reduce the time for deposit and withdrawal.
Although they have highest measure of security and they keep all their funds in cold wallet to prevent hack but that caused delay.
I am sure once the improve this, there is not stopping decoin getting on top 20.