We thought it was noisy - and not the first week in June either - middle of October before F&W started last year. I also had a four year old. She was so tired she slept through the noise, but it was noisier than I would have liked. Particularly the fireworks - although I don't know that there would be a room in the Epcot area that wasn't noisy when fireworks were going on - but also just the people coming and going, the noise from the games, the noise from the street entertainment.
So, while it didn't bother the kids - it bothered me - but some of what bothered me was worry that it would wake the kids (if you know what I mean).