I just installed WordPress version 3.9 and I'm already disappointed!
Issues so far:
1.) The font sizes are all wrong! 12 pt is not actually 12 pt and 14 pt looks more like 18 pt! How is that even possible?
2.) They took out the option for padding for images uploaded to a post? Why would they do that? We need the ability to change the padding between text and images in our posts!
I found these issues in the first 5 min of updating WordPress and posting on my website. I'm sure I'll find more issues as I update my site.