[Nexus 4 General] Nuu~:
Well, it boots but all it really is is a "what it should look like when it's finished in 2014"

What works:

It boots

It looks exactly like in the demos. It even has the same notification, contacts, photos, video samples etc. preinstalled.

WiFi works

The browser works too, but is horribly slow

The gallery works

The notes app works

The camera works, but is quite bugged

Twitter, Facebook and eBay are practically just links to their mobile webpage

What is broken:

Radio does NOT work (internet, phone calls etc.)

Nearly every app that is not listed above is either broken or just shows a sample image of how it will look like in the future

USB does not work

Modifying the contacts or adding new ones does not work

Sending messages or calling people does not work (see above)

Video player just shows a black screen (actually it seems to show the controls, but none of them work)

Music player just shows a picture of how it will look like

Searching does not work properly

It seems like it has no access to your media files in your internal storage

The "welcome screen" does nothing but showing "14 new tweets" all the time

You can't click on some installed apps, therefore they simply won't launch

Clicking on the suggested apps to install does nothing

As you can see, it really only is a developer preview, or more like a design guideline for future developers.

We'll see what the official version that will be released at 4pm has to offer, although I don't believe that it will be any different than this build.

The performance in the few apps that work (native apps like the gallery, that is) is pretty okay for such an early build. Occasional stuttering happens on some pages on the homescreen though. The non native apps (aka links to the mobile webpages) have a pretty bad performance, which probably has something to do with the slow browser in general.

The gestures are quite nice to use, but still need some improvement before the final release. Especially swiping from the right, as it gets triggered way too easy (pressing a button near the right edge is enough to switch to the previous app, which is quite annoying when you're browsing the web and want to click on something near the right edge)

If you still want to test it on your phone, here is a small guide on how to do it:

Your personal data (pictures, music etc.) will not get wiped if you do it that way.

-Back up your current Android ROM, since you can just restore the backup later when you want to get back to Android from Ubuntu.

-Boot into your recovery, do a factory reset and wipe "system"

-Reboot to the Bootloader and make sure that Fastboot works on your system

-flash the kernel: "fastboot flash boot quantal-preinstalled-boot-armel+mako.img"

-flash the system: "fastboot flash system quantal-preinstalled-system-armel+mako.img"

-optionally you can flash their recovery. Not needed if you already have CWM installed: "fastboot flash recovery quantal-preinstalled-recovery-armel+mako.img"

-the names mentioned above may vary depending on what you called them while downloading

-Once you're done, boot into CWM and flash both zips that were linked a few pages back (i flashed the big one first, the small one after that. did it the other way too, and it didn't make a difference at all)

After that, you're ready to boot the device. There is no bootanimation, so there will be quite a long black screen in the beginning.

If you want to go back to Android, just reflash the backup you made earlier.

The files can be found here. Canonical pulled the files from their official FTP shortly after they got released: