From a pax perspective I clearly remember my first ever flight on an A340. As we trundled down the runway I became convinced that the crew intended to drive from Frankfurt to Seoul, so poor was the acceleration. And that was an A340-600, so God knows how bad the CFM engined versions feel.
In all fairness though after it clawed its way into the sky it wasn't a bad aircraft to fly in. Just a little disconcerting the first few times with the apparent lack of acceleration compared to other types.