I was just looking at the wait times at MK at 9AM EST, one hour after park opening and 2 hours after EMH opening.
7DMT had a posted wait of 60 minutes and an actual wait of 37 minutes. Long but not ridiculous for someone who really wants to ride.PP had a posted wait of 40 minutes and an actual wait of 27 and everything else had a posted wait of 20 minutes or less and an actual wait of under 10 minutes.
In other words, everyone who was willing to get to the park by 7AM, or 8 AM if staying offsite, had a golden opportunity to enjoy several of the most popular attractions in the park with minimal wait and no FPs. Then if those guests made their FP+ reservations for later in the day they would have the opportunity to enjoy 3 more major attractions at a time when standby lines are much longer.
People who don't want to get to the parks early, but still made their FP reservations, will still be better off than they would have been arriving later when paper FP was in place.
I would make the argument that FP+ makes visiting MK at the busiest times of the year more enjoyable for a high majority of guests. I am still waiting for someone to report that they tried to make FP reservations for MK the day before their visit, or upon arriving at the park at opening and were not able to get anything good. If the only things not available are 7DMT, A&E, and parades and fireworks (all things that were not around or didn't have FPs before this year) that sounds pretty good to me.