Ireland lost 2-1 to Turkey in their previous friendly but put in an improved display against Italy at Craven Cottage and carved out some good chances to win.
Stephen Quinn's effort hit the crossbar with 12 minutes remaining and they ultimately had to settle for a draw, but O'Neill was happy with how they performed.
"I thought we were excellent," O'Neill said. "We could have scored a few goals.
"I'm really pleased with the way we played against Italy.
"I thought the game was very competitive from start to finish, just what both teams wanted.
"Italy are preparing for the World Cup, while we were looking for a boost in confidence heading into our Euro 2016 qualifying campaign and we got that.
"I think in the recent games that we have played, apart from the one against Poland (a goalless draw in November), we probably should have won all of them considering the scoring chances we've created.
"I hope we are saving those goals for our European qualifying campaign."
Ireland will have Robbie Keane available for the friendlies against Costa Rica on June 7 in Boston and against Portugal three days later in New York.
Keane, who is the country's all-time scorer, is playing with club side Los Angeles Galaxy.