We've done FP+ for FOF a few times and like that we don't have to stake out our spot an hour or so before the parade begins. The view is great with the castle as a backdrop and they don't cram the space too full. HOWEVER, I highly recommend arriving to the space BEFORE your FP+ tells you to arrive. Both times we arrived right at the time our FP+ said (I think 2:45 for the 3:00 parade) and we got some of the last space 'on the rope.' People who arrived shortly after would have to stand behind those of us seated at the ropes. The area isn't packed and you can stretch out some, but if you want your kids to be close enough to get the character interaction on the ropes, you'll want to arrive a bit earlier..
Also note, the reserved section has ZERO shade, so come prepared. Bring something to sit on (a towel or blanket because the ground is HOT) and bring water and possibly a parasol or something for shade. Spritzing fan and a chilly pad come in handy, too.
I will add, we've also used FP+ for the MSEP and it's great. That night they held everyone with FP+ outside of the reserved space until about a quarter til, whereas it seems for the afternoon parade they let people in much earlier.