I'm here to say that there are many features I cannot comment on, do not use, and will not be testing now:
- 4K screen support
- 15" macbook pro retina screen support
- better support for smb shares, network home directories, AD (Active Directory) groups - not something I'm dealing with at this time
- better IPsec VPN support - I use one, but had not seen problems and still see none
- Post Script Type 1 fonts
- added (back?) syncing calendar and contact via OS X and iOS - I use iCloud, so, I do not do this.
- More data about security updates are not yet posted - I look forward to reading it when available: Apple security update list page
What is in there?
- Safari 7.0.3 -- This is all about security updates. I am not testing at the level needed to verify; I will just enjoy better security for these issues. They are critical - arbitrary code execution fixes always are.
- iTunes 11.2
- It is reported to have security fixes that stop people who could have gotten your iTunes credentials - see here.
- A hangup while performing Genius updates is supposed to be fixed. That is very welcome
- This update seems mainly about an improved podcasts interface. There are buttons when looking at the podcast view to see what you want, and another improved settings interface accessed with a button.
- View: Quickly find unplayed episodes
- Settings: Save episodes, Auto delete episodes that have already been played
My first use of iTunes 11.2 meant that hitting the iTunes store was very very slow. I believe this was due to an attempt to download a ton of podcast content I had just set to not be downloaded... I mostly do podcasts on my iPhone; I don't need them on my computer.
After getting in, I hit up an ad for the new Coldplay album, Ghost Stories, via an iTunes Radio feature, First ->Play. This is not really a 10.9.3 thing, but it is the first time I happen to have seen this.
UPDATE: check out this article if you cannot find /Users in finder: Apple Insider - 4.9.3 bug and work around