I've recently switched to i3 on my work laptop, and it is a dream to use! Well, the windows management part of it, anyway.

What I miss most from Unity Desktop is the nice looking system tray I had, where I could click on the sound icon to control the volume and the playback status of all my music applications. I miss that I can click the time and date in the system tray to see the calendar. I miss that I can type "photo" in the dmenu and get all my photo related applications listed. I miss that I can resize my desktop to any number of screens on the fly without having to type out a bunch of xrandr commands just to get my screens to work.

I miss that I can just set or unset if my screen will lock after 5 minutes or not. I miss that I don't have to do a bunch of "bindsym X86WhateverThiseverButtonIsCalled" to get volume and brightness control to work.

Somebody else already invented the wheel. Why do I have to reinvent it again in my config files?

I really wish it was possible to use tiling in a shell that was more modern. Like Gnome3 or Unity