I just successfully upgraded my MacBook Pro (Retina, 15-inch, Mid 2014) running High Sierra latest release to Mojave. Download of Mojave only took a few minutes, perhaps 3-5 minutes. Installation took about 40 minutes total.
09:42 Started Mojave installation on MBP
09:46 MBP restarted
10:13 MBP screen briefly went completely black (for about 10 sec),
10:15 MBP screen went completely black (for about 45 sec)
10:22 installation completed and the sign-in screen for Mojave displayed
I didn't use the beta version, so this is my first look at Mojave.
I'm not all that impressed with the Dark Mode. It is a good start, but they need to add some customization. For example, the light colored text is too bright with the dark background (too much contrast) and causes the "mini blinds effect" with my eyes. I see no way to make the text a little less bright. Also, Safari will display web pages how they were specified by the designers of same, so you will still get bright white pages that don't really fit into Dark Mode very well. They need to rethink Dark Mode, add customizations for text color/shade and add the ability to darken bright pages and app interfaces. Otherwise I won't be able to use it much, if at all.
The new screen capture function (Command + Shift + 5) is an improvement, but when I captured the attached About This Mac window using the Capture Selected Window option, it also captured at least 1/2 inch of screen all around it. BTW, I cropped the image before posting it. That is clunky and shows how the Apple programmers just are not that good sometimes. They need to fix that. Geez MS has been able to that correctly for over 20 years!
I haven't had time to test out Mojave much yet, but so far no issues. I tried running Excel 2011 for Mac which is a 32-bit app and it seems to load and run okay, and without any warnings about it being 32-bit. So that is good. I hate Numbers as it is too clunky to use.
One thing I will warn you about though, and this goes for any Mac OS X update, be sure to have your current passwords written down so you can refer to them during the installation and/or setup of the update. With Mojave I only needed to enter my Administration Password for my MBP, and all went well. With High Sierra I was asked for the Administration Password for my MBP, the Apple ID Password, and the Encryption Password, and I had no idea about the Encryption Password even existing much less what I had used. So I was locked out of my MBP until I spent 30+ on the phone with Apple Support and finally got every necessary password reset. Apparently a rare glitch occurred when installing High Sierra that caused the MBP to somehow use an older password. What a mess, but it got resolved fairly easily. But again, I had no issues at all installing Mojave as it went fairly fast and flawless.