I think, and could certainly be wrong, that if you are the type of guest who took full advantage of Fast Pass - arrived at rope drop, used upwards of 6 fast passes a day (and more at MK since they had the detached fast pass rides), used multiple fast passes for a ride, etc. - you aren't really going to be a fan of FP+. Now, if you are the type of guest who enjoys sleeping in, leisurely arriving at the park at 11:00 or later, you often enjoy FP+. My family happens to fall into the former category and we found that FP+ did negatively impact our touring 2 weeks ago. I kept getting assurances that they had't finalized FP+ and that they were still taking feedback to make changes, but all of the FP machines seem to be gone. So, unless they are going to really change how you do FP+ in that you can have 10 a day and multiples for the same ride, I don't see it really being a better system for my style of touring than the legacy fast pass.
Edited to add: We were told on multiple occasions that a study was done that found that the average guest only used 1.3 Fast Passes per day. Now, I don't doubt this to be true, but I'd be willing to bet that that average is because there were people using 6, 7, and 8 and then MANY people who used none due to believing you had to pay for it. I don't think it is in the best interest of Disney to limit it to 3 since the average was 1.3 per guest. That average means that there were plenty of guests who used fewer, which means that they won't care that the limit is 3, but also that there were many who used more who would be angered by the limit.