Yes, it is still Easter. The Octave of Easter lasts through Divine Mercy Sunday (the first Sunday after Easter), where all of the days are celebrated as Solemnities.
Not only that, but the season of Easter lasts for about 50 days. The celebration of Easter goes even further than the celebration of Lent. Defeat and death are swallowed up and destroyed completely by the victory of Christ. Our celebration has the greatest of causes. So I say again-Happy Easter!
“We are an Easter people, and Alleluia is our song!” -Pope St. John Paul II