I'm eager to see what might need "fixing" with Mojave, especially given I haven't encountered any problems yet, but everyone's circumstances/situations are unique to themselves.
I've read about a few problems and even posted a blog about them, but they don't apply to me.
On further reflection, I believe the only thing I'm disappointed with concerning Mojave (and iOS 12) is that I thought Siri was supposed to receive a major overhaul and a ton of advancements. The Siri Shortcuts app for iOS 12 wasn't what I was expected, and it isn't what I wanted.
Siri Shortcuts is extremely unintuitive. Either that or I'm a moron. Even with detailed instructions, I'm having trouble getting the "Police" shortcut to work as advertised. (This shortcut allows for using one's iPhone as a body cam in the event of being pulled over in a traffic stop, and sending an e-mail, text or other alert to a third party. My wife's nephew is the Chief of Police here in our town of 35,000, and he thinks its something that should catch on with the public. In fact, he hopes it does.)
At the same time, I've learned over time that Siri can be much more useful if one takes the time to learn a few tricks about how you speak to her and how you ask her questions. (Yes, I personified Siri. I offhandedly thanked Siri for something or other a couple of months ago, and she replied with something like: "You're very welcome. After all, you are the wind beneath my wings." I was stunned. My wife completely lost it and now teases me endlessly about "our relationship" every time she hears me ask Siri something.)