。
You really did a great job, didn't you.
Literal
Truly well do-[for-me-てくれた] [agreement-ね].
よくやった by itself is a common 'well done,' but here the benefactive ~てくれる ('did for me/us') adds the nuance that the listener's good work was a favor to the speaker. Final ね softens the praise and invites shared appreciation. A warm, casual compliment from a superior, parent, or team member.