(1) After you've made your G+ selection you can't modify it. You can only cancel it and hope that you'll be able to get a better/later/different time, but maybe you won't be able to.
(2) G+ seems to work best for people who either stay from open to close or who hop and are able to make a stack for the attractions they want in the hopped-to park. If you're not that person, then G+ is not working all that well for you. G+ also works well if you don't care what attraction you get or where it is relative to where you are when you book it.
(3) There's weird downtime involved, where you're between your last G+ and your next one and you're too far away from an attraction you'd do standby for since then you'd have to walk an extra couple of miles.
(4) You cannot plan ahead. You can't even plan ahead at 7 a.m. since you might not get what you want at a time that would work out for your plan, whatever that plan is. You need to start the day with at least a plan A and a plan B. Even better if you also have a plan C.
(5) The park reservation system makes all this even harder, especially if you don't have a hopper or an AP. Now you can't even see if you could perhaps get a better selection of rides at a different park. You're stuck with the park you reserved.
(6) Being lied to. G+ was sold as something that would even the playing field, yet if you can't afford it, then your playing field has been crushed, not leveled. What's an extra $15? you might ask. Well, if you have a family of 4, you've just added $60 (actually, it's $63.92, with tax) to just one day of your trip. Sure, you could just do standby, but here we're in the FP+-was-free territory. It was free and it worked for everyone.
And, as for the lie, G+ is actually something that was created to make money for Disney. Period.
I think the FP+ preference ideas were already covered in this thread. For people who like to plan in advance--even a little in advance--FP+ worked much better. Yes, people who stayed off-site had a disadvantage with FP+--although I had many trips that I planned less than 30 days in advance and I was still able to make almost all my FP+ selections with some perseverance--but off-site guests have a huge disadvantage with ILL$, since RotR is nearly impossible to get for anyone not onsite, FoP is very difficult, and I gather that 7DMT is no treat, either. I realize ILL$ and G+ are separate things, but they serve a similar purpose.
For Disney parkgoers who have the money to spend, G+ and ILL$ aren't a financial burden. But for some of us, we've cut down on other things we used to spend money on at WDW--like TS meals and resort category. But I gather that Disney has decided it doesn't care about repeat visitors since onetime-only visitors, per their research, spend more money.
Wait until so-called revenge travel ends. You will start seeing real discounts across the board at WDW.