The Cherries were behind after 11 minutes when Kevin De Bruyne opened the scoring with a low free-kick, and Howe's side were unable to respond to the early City pressure.
Kelechi Iheanacho, Raheem Sterling and Ilkay Gundogan added further goals, but Howe says there will be plenty to reflect on from a mixed display.
"It was a tough day," Howe said.
"They were excellent, but from our perspective one of their goals is a free-kick gone under the wall, the other is from our own set piece. The nature of the goals is disappointing."
"We had some good counter attack opportunities and didn't make the most of them.
"There were moments when we did OK, but they weren't enough, we turned the ball over too much, particularly in the first half.
"There's always things that we can reflect on and improve.
"Obviously they were very good today, it didn't help that we weren't at our best and we will have plenty to look back on."
Howe also handed Jack Wilshere his first Premier League start, and said of his performance, "It was difficult for him, as his best assets are when we have the ball in and around their goal.
"Everyone will want to learn from this defeat."
