I tried Plasma Mobile on my Nexus 4. I just followed the Halium docs. Compiling Halium took a long time and chewed up most of my the space on my SSD, but it was otherwise painless to build and install.

I couldn't get voice calls or mobile data to work. There wasn't even any mention of modem in Halium's porting docs. I tried asking around on IRC in #halium and in #plasma, but no one responded. Is modem working properly on Nexus 5? It didn't appear to be in the screenshots I've seen.

I had to manually enable the wifi on every boot by using some arcane command.

Launching the camera program caused the whole thing to reboot.

Being able to apt-get whatever the heck you want from the ubuntu repos is pretty cool, but there are some issues with XWayland. For example, some GTK programs displayed only in tiny windows in the corner of the screen.

XWayland didn't seem to know when the on-screen keyboard was being displayed, and clicking the enter key would also activate the close-program button.

Chromium and Firefox were pre-installed in the pm-rootfs tarball. Chromium worked okay (except for the above-mentioned keyboard issue), but FF consistently crashed on launch.

Rotation wasn't working, but IIRC, it seemed like I was getting good data from the sensors.

apt-get upgrade caused the device to boot loop.