I'm updating to Kubuntu 16.04 LTS right now.

Yay, I've been waiting for this. 
I felt Kubuntu 15.10 is a bit unstable. So I have high hopes for the new LTS release. I'm doing a direct upgrade.

Even though I'm using i3 on Kubuntu, I welcome improvements in stability for QT related software.
Another standard font. Looks very nice together with i3.

Update 2016/04/22: Upgrade successful. Working fine together with i3. The new default fonts and sizes are great.

Update: 2016/04/24: Speed is decent. On Chrome I can feels some very minor hiccups on scrolling webpages sometimes. Have to determine what's the reason for that, but it is almost not recognizable. No worries. Added Screenshot.