Re: Boots quickly in VirtualBox...
"Anaconda is still pointlessly shouty (lots of headings entirely in capitals for no good reason) and the custom disk partitioning is painful - no obvious option to use all remaining space on device for a partition. I ended up putting in a big size value and let it truncate it down, but that's not great. They're still annoyingly mixing size units (K, MB and GB all on the same screen) too :-("
Again, you can just enter no size at all and it will use all remaining free space. And again, I don't see why you think it's wrong to mix size units. It would make no sense to list a 1MB partition as '1000KB' or '0.001GB', would it?
"Still no package size or description is displayed when the packages are being installed"
And I still don't see why you think there's any particularly good reason to do this, other than making the installer look busier.
"Am I the only one who actively dislikes those white/blue coloured multiple progress bars at the bottom of an otherwise black screen when Fedora boots (yes, the ones that tell you zero about what's going on)?"
Probably. You seem like someone who REALLY CARES A LOT about things that seem really pretty trivial (like, er, all of the above). For the record, though, you only see that screen if kernel modesetting is not working - so basically, usually only in VMs. On actual machines, you get a fully graphical boot splash which is just a big blue screen with the Fedora logo in the middle.
"When I first logged in, I got about a dozen file explorer windows open (this is a known bug that will be fixed, but it just looks sloppy, even for a beta)."
It's also only in MATE, which is not a top-tier supported desktop (in Fedora, GNOME and KDE are supported the most strongly - they're the only desktops in which bugs can block the release - followed by Xfce, LXDE, Sugar, MATE and Cinnamon in about that order). We run a six month release cycle, we have a test team of about a dozen people inc. paid and volunteers, and Fedora includes at least a dozen desktops; there's a pretty hard limit to how strongly we can test them all for a beta release. And it wouldn't have really served any purpose for anyone to delay the Beta release just to fix a superficial bug in MATE.
"I also got an immediate SELinux balloon warning which is bad for a vanilla install"
Again, that doesn't happen in KDE or GNOME; it's actually tied to the lightdm login manager. We were tracking this bug prior to release and the lightdm that shipped in Beta was actually meant to fix it, but the packager made a mistake and inadvertently left the fix out of the build we shipped. The bug is https://bugzilla.redhat.com/show_bug.cgi?id=922958 . Xfce, MATE and Sugar use lightdm in 19. The AVC is actually basically harmless, it doesn't affect functionality of the system at all; you don't have to turn off SELinux just because you saw an AVC, in fact that's almost always the wrong response. It's much better to report it and follow the report. They are usually resolved very quickly.