The 61-year-old says he is pleased with his team's performance after bouncing back from a sluggish opening to their World Cup qualifier
Oranje won the match 4-1, with goals from Jeremain Lens, Bruno Martins Indi, Rafael van der Vaart and a late strike from Robin van Persie sealing an ultimately conclusive victory.
"This is a great achievement," the former Ajax midfielder told SBS6. "We did not start so well.
"But luck was on our side. Then we got better in the game and we saw it coming. They were incredible goals. Lens' [goal] for example, who never [scores] headers.
"I thought in the first quarter we were restless, which I had not expected. But we had problems getting the ball forward.
"Romania are organised, so maybe that's the excuse. In addition, the stadium was beautiful but the pitch less so."
The 61-year-old also singled out Nigel de Jong for praise, having criticised him following his side's victory over Andorra.
"Nigel de Jong played a very good game," praised the former Bayern Munich trainer.
"He played the ball far better than against Belgium and Andorra.
"Overall I am very happy with the second-half because we killed the game and gave little away."