Pros: Longer hours, more attractions open.
Cons: Hot, humid, crowded.
I agree with the strategy of getting there EARLY, leaving in the middle of the day, coming back or going to a different park in the evening.
If you can do Early Entry, that is a good strategy. We've done Early Entry, then left after we finished the attractions that were open early and gone to another park.
We've found that we can stay up late for parades/fireworks after our afternoon nap/swim time.
Utilize Fastpass whenever you can. We try to get a Fastpass, then eat, or do a parade, while we are waiting for the time to come up.