You'll ride it via FP+, faster than you would have ridden it via Standby, before.
As an example, the HM tends to be a 45-min wait midday. It was in 2010, it was in 2012, and it was in 2015. Now, midday, you can ride it in 20 via FP+, while sb might take 55 min. In either scenario, you could ride it between 9am and 10am in 25-minutes. So it's all what you make of it. You CAN ride the HM, now, in less time than the same time-of-day wait would have been in 2012, but you also could have ridden it in 2012 at a more opportune time, thereby not needing a ticket for it. You can also, today, ride it at a more opportune time and still do it in 25 min w/o a FP+ if you want. What has changed, is that if you want to ride it midday, now, you can... with very little wait, if you pull a FP+ for it.
It's not rocket science. You just do your best job of picking the rides which will save you the most time for how you tour.
Keep in mind I'm not saying it is an end-all save-all for everyone! If you used to pull a LOT of FP- tickets, then FP+ is designed to keep you from doing that! It is designed to take all those beyond 3 that you used to get, and ensure other guests have an option to get them before you can get your 4th, 5th, etc. This is good for most guests, but bad for you. Best thing you can do is try to figure out the system and understand it better than the average guest. That's where you'll get your advantage, just like with FP-.
I don't get the concept behind repeatedly bashing FP+ instead of taking a pragmatic approach of... Okay. Here's the system. How do we get more than the average guest. (?)
FP- was great. I loved it, really. I have the pockets-full-of-tickets that we'd leave the park with in our scrapbook. They were very fond times. But it is a new age, and we can dwell on the past or figure out the FastPass of the information age. As great as it was, I totally understand that Disney wants every guest to get some even if it's just 3, before some guests get 12. That just makes sense, and it means once everyone gets 3, you can't get 12 any more. Such is life. They built a BETTER SYSTEM. Let's beat this one now. Yes?