We'll be taking our 4th May trip. Not sure when you usually go but May is warm but not as humid as summer months (although last May was pretty humid). Crowds will be moderate but more than you'd find in winter and fall.
We have always experienced more rain in May than any of our other trips (we usually go in January and in the fall). Also, there could be lovebugs there. We've had them once but they don't bother us.