Is the New Covenant a unilateral or a bilateral covenant? The Old Covenant was a bilateral covenant of which Yahveh and the nation of Israel were parties. The Israelites had to agree to the terms of the covenant, which they did (Exo. 24:7).

Is the New Covenant a bilateral covenant?
Yes, it is a bilateral covenant! This is the new covenant, Jeremiah 31:31-34 (NIV) :


  “The days are coming,” declares the Lord, “when I will make a new covenant with the people of Israel and with the people of Judah. It will not be like the covenant I made with their ancestors when I took them by the hand to lead them out of Egypt, because they broke my covenant, though I was a husband to them,” declares the Lord. “This is the covenant I will make with the people of Israel after that time,” declares the Lord. “I will put my law in their minds and write it on their hearts. I will be their God, and they will be my people. No longer will they teach their neighbor, or say to one another, ‘Know the Lord,’ because they will all know me, from the least of them to the greatest,” declares the Lord. “For I will forgive their wickedness and will remember their sins no more.”


This new covenant started when Jesus poured out his blood (symbolized by the wine in the last supper), Luke 22:20 (NIV):


  In the same way, after the supper he took the cup, saying, “This cup is the new covenant in my blood, which is poured out for you.


All we have to do to accept this new covenant is stated in Romans 10:9-12 (NIV):


  If you declare with your mouth, “Jesus is Lord,” and believe in your heart that God raised him from the dead, you will be saved. For it is with your heart that you believe and are justified, and it is with your mouth that you profess your faith and are saved. As Scripture says, “Anyone who believes in him will never be put to shame.” For there is no difference between Jew and Gentile—the same Lord is Lord of all and richly blesses all who call on him, for, “Everyone who calls on the name of the Lord will be saved.”


Jesus basically stated the "terms" in John 15:5-7 (NIV), though not speaking specifically about a covenant:


  “I am the vine; you are the branches. If you remain in me and I in you, you will bear much fruit; apart from me you can do nothing. If you do not remain in me, you are like a branch that is thrown away and withers; such branches are picked up, thrown into the fire and burned. If you remain in me and my words remain in you, ask whatever you wish, and it will be done for you.