O'Neill reassured fans that he's aiming to restore Villa's glory days - but it's a long-term task.
"The club is in really good hands," he said. "I don't think everybody thought we were going to sign 19 players in January.
"It's obvious we need to strengthen. In the summer we can strengthen again.
"Even Sir Alex Ferguson said it was the smallest squad we'd had, and his view was we'd done remarkably well."
And he insists he's not bothered by the criticism.
"If someone doesn't choose to believe those reasons, it really doesn't bother me," he added.