Several people in our family (us included) have been to WDW mid-May. Sometime around Mother's Day, the parks lengthen their hours. In April they may be closing roughly an hour earlier. So going the 2nd week of May gives you the opportunity for a longer day in the parks. Also, each day at this time of the year has just a little bit more daylight time. So the closer to summer you get, the more daylight you'll get. (That's a biggie for my MIL, who's vision impaired and needs more bright light.) And, it's just a little bit warmer in May - daytime highs have often gotten up to 90 when we've been there.
DH and I spent our honeymoon at WDW in late April. Have since been twice with kids/grands in mid-May. Of the two, we prefer mid-May. Either way, it's a good time to go - after Spring Break and before Summer Vacation.
90 honeymoon
95,98, 01 w/kids & grands