We have been to Disney twice since the start of Genie+. It is better than I thought it was going to be, and I feel like I have (through a ton of research and some trial and error) come reasonably close to maximizing its value. I've used every trick in the book to significant success. But all told, I'm still not a fan.
Here are my biggest concerns:
(1) In order to get the maximum benefit, you have to wake up before 7:00 each day, no matter what your plan is for that day. If you are rope-dropping for early entry, that might not be that big a deal (though it can be a hassle if 7:00 comes when you wanted to be in the shower or the car). But if you were hoping to sleep in, or had been out late the previous night (for instance, for extended evening hours), it can be brutal. There were multiple days when I was planning to go right back to sleep after booking my first LLs. But the adrenaline rush made that impossible. And it meant that I was cranky and sleep deprived throughout the trip. Hardly a vacation. FP+ was way better in this regard.
(2) In order to ride the best rides without waiting in crazy lines, you need to pony up ILL$+ money in addition to Genie+. I'm someone who is willing to pay extra to skip lines. But the cost of G+ plus two ILL$+ each day really adds up. I'm not sure the value is really there.
(3) Not being able to choose your times can wreck havoc with your ADRs. Very stressful and frustrating.
(4) I hate that the time that you click is often very different from the time that you actually get. Bush league. Disney should at least hold the time slot until you finish the reservation, the way they did with FP+. Sometimes you click on 11:00 and they give you 4:30. Not cool.
(5) It is very frustrating that, especially on busy days, you often have to choose between number of LLs and quality of LLs. It's easy to get LLs for things like Buzz, Spaceship Earth, and Star Tours. You could do a bunch of those, or you could do rides like SDD or PPF or MFSR. But if you choose the latter, the very late return times, combined with the 2-hour cooldown window, mean that you end up getting many fewer LLs. And it is very hard to get, say, both MFSR and SDD in the same day. So "one LL per ride per day" ends up being a pipe dream. That combined with the exclusion of the ILL$ rides really decreases the value of G+.
(6) I had many IT problems during my trips. The app would freeze or get stuck in some sort of loop, and the best time slots would slip away while I was powerless to do anything about it. If I'm going to wake up at 6:45 after a late night, or set my timer for 2 hours and interrupt a sit-down meal, I expect the system to work as advertised. Many times, it didn't. Don't charge for a service that you can't consistently and effectively provide.