We've now had two experiences with fp+. Last Sept/Oct(experience # 1), and just a few weeks ago(experience # 2). The most recent experience was far superior to the previous but that may be more in the nature of our plan rather than fp+itself.
Experience 1....we hated fp+. We hated the lack of spontaneity, we felt scheduled, and we found ourselves unable to accomplish anything close to what we had been previously able to do pre fp+ because of the length of standby lines.
We decided that wouldn't work for us again and as a result made some changes. Understand this worked for us(sort of) but might not work for others if you want long park days . We simply did not wish to be frustrated on a vacation again. We decided that we would simply plan for very very short park days and only do our must do's. Instead of taking 5 or 7 day tickets we decided on only 3 days at Disney (and the rest for Universal which for us with express pass was a far superior experience)
Our first day was MK(arrival day) and we booked 3 fp's with plans for only 2 other rides. Standby lines were shorter than they had been on exp 1 and so we were in and out of MK within 2 and a 1/2 hours. Epcot was even easier. We only used our Tier 1, and only did one ride standby then on to pavilions and dinner at MP's. We decided to not bother with our last MK day since dh wasn't feeling great and we couldn't reschedule the fp's we had (or BOG) for another day...and yes I did check but we had 7dmt, and wishes.
So for our arrival day fp+ was fine for the touring we did do prior to dinner at Cal Grill. It was fine for the time we used it at Epcot. We couldn't reschedule our 3rd day so we just wrote off that day.
Overall Ive warmed to it and Im so happy Disney implemented it. It allowed us to rediscover Universal(for which I am eternally grateful), and allows us to just "pop in" to Disney for a few hours which is all we'll be doing in the future now

. We're also spending far less money with Disney now too so that has to have a pretty big value....although I must admit that Universal is now getting most of that
Next trip it will only be 1 Disney day so I expect fp+ will work even better for us then too !