We just returned from a week long trip at the parks. I thought security was great.
Everyone was checked before entering transportation at the TTC. We were bagless and had to go through metal detectors each time, as did random people who had gone through bag check.
There were police with dogs outside the ttc (I assume they were bomb dogs, but could have been drug dogs, idk).
The security lines moved much more quickly and efficiently than when it was directly in front of MK entrance, and while there was still a large crowd, there was also a large armed security presence and plenty of places to run and hide.
Ultimately, if someone wants to do something horrible, they will find a way, whether that be flying an airplane into a building, shooting up a concert, bombing a marathon, driving a car into a crowd, etc. I'm a worrier, and a million scenarios of what a crazy person might do to attack Disneyworld have run through my mind, and ultimately there is just no way to defend against every possible threat.
So we go to the parks, have a blast, and take comfort in the fact that this likely isn't the day that someone will act on their plans. Statistically many other things are more likely to kill me before a terrorist attack at the happiest place on earth.