Apart from the lack of an annual option which is a major issue, there's also major changes to the rules and how return times work. A savvy Maxpass user would be able to stack Fastpasses throughout the day, optimize for Multiple Experience passes and other things being equal, get significantly more Maxpasses per day (it was possible to get over 30 Maxpasses in a day). The changes make all of these significantly harder.
As an example, in the past, I liked to grab a Space Mountain Maxpass at rope drop and then 30 minutes after park open, grab a Star Tours Maxpass. Then, I could use both of them around an hour after park open. This is no longer possible because instead of allowing you to get your next Lightning Lane after the start of your return time, you have to use your previous Lightning Lane assuming the return time was less than 2 hours away. I would have to use up my Space Mountain Maxpass before I could get my Star Tours one. Additionally, doing this with Genie+ means I can't get Lightning Lanes for either of those rides again later in the day.
That 2 hours is also a change from the previous additional Maxpass which was 90 minutes. So let's say it's 1PM and I got a Maxpass with a return time at 2:45PM. Under Maxpass, I could get a new Maxpass at 2:30 but under Genie+, I would have to either use the Lightning Lane starting at 2:40PM or wait till 3PM.
The rules around ride breakdowns also aren't clear yet but no matter what they do, without being able to get passes for the same attraction multiple times, it's harder to get Multiple Experiences passes.
There's also the change of upcharging for Radiator Springs Racers. It used to be included with Maxpass but is not anymore. With only 7 Lightning Lane rides in California Adventure and no re-rides, Genie+ is a significantly worse value compared to Maxpass if you aren't park hopping.