The European Commission says "good progress" has been made in implementing its deal with Turkey, which aims to cut the number of migrants heading to the EU.
The executive made the pronouncement on Wednesday as it unveiled its first assessment of the EU-Turkey agreement.
It cautions, however, that "continued efforts and commitments" will be needed to carry out the "sustained return and resettlement operation."
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So far, the Commission says that 325 irregular migrants arriving to Greece via Turkey after 20 March have been returned to Turkey under the terms of the agreement.
Frontex has deployed 318 escort officers and 21 readmission experts to the Greek islands to support the return operations.
Some 60 asylum officers and 67 interpreters have been deployed to the Greek islands to support the processing of asylum applications.
In addition, a total of 25 Turkish liaison officers have been deployed in the Greek hotspots and five Greek liaison officers to arrival points in Turkey.
So far, 103 Syrian refugees have been resettled to the EU under the scheme.
The agreement was thrashed out on 18 March when EU heads of state and Turkey agreed to end the "irregular" migration from Turkey to the EU.
The Commission says, "This new approach has started to deliver results, with a sharp decrease seen in the number of people irregularly crossing the Aegean from Turkey into Greece."
Further comment came from European Commission First Vice-President Frans Timmermans, who said: "The first result of our cooperation with Turkey is that the message is starting to get through that turning to smugglers is the wrong choice to make."
The Dutch official said, "In the past three weeks we have seen a sharp decrease in irregular arrivals, which now needs to go hand-in-hand with opening up the legal channel of resettlement to those in need of protection.
"Although we have seen good progress in the initial stages of implementation, the Commission will remain engaged to ensure full and timely delivery of all elements of the EU-Turkey statement, including projects for refugees from Syria in Turkey, the visa liberalisation process and compliance with EU and international laws.''
Ahead of Wednesday's announcement, Commission President Jean-Claude Juncker met Turkish Prime Minister Ahmet Davutoglu in Brussels.
After the meeting Davutoglu insisted that Turkey had "fulfilled all its commitments in the deal".
He said, "The number of crossings from Turkey to Greece has gone down to 60, and sometimes zero, people a day. This is a successful deal."
Under the agreement, the Commission has agreed to speed up the visa liberalisation progress for Turkey and says it will make an announcement on this on 4 May.
Turkey says it expects the EU to ease visa requirements for its nationals by June but Juncker said that Turkey should not expect special treatment on visa-free travel for Turkish citizens in Europe.