We have been to the parks during the last week of April the past 2 years and LOVED IT!!
The crowds seemed to be perfect, the weather was awesome (not a drop of rain) and day-light savings time was already in effect.
Just beware that they host a lot of graduation nights for high school seniors this time of year. On Saturday night, April 29, Magic Kingdom closed at 7:00pm for a HUGE graduation night. These nights can impact how late the parks are open and cause the other parks to be more busy.
We stayed at a DVC resort and didn't see/hear any teens but I heard several complaints about obnoxious teens from guests that were staying at the value resorts. It was also music festival week while we were there and I would assume the "problem" teens were with the band/choirs that were on property as I don't think the seniors spend the night??