I'm also running the Android L dev preview via MultiBoot. My thoughts:
I love the design- the animations, effects and transitions are much improved, basically iOS-esque in terms of polish. They add a whole new layer to Android from a design standpoint. It also has a much cleaner, less cluttered feel. Even the new multitasking menu feels simpler to use, simply because the design and flow is similar to other Android apps (notably Chrome). It's still missing a few things here and there (a clear all button would be nice in the aforementioned multitasking menu; a few elements of the UI still exhibit the Holo Blue design) but for the most part, it looks damn good while still being immediately familiar.
The colour scheme is not as overtly different and jarring as the iOS 6 to 7 jump was. The palette is brighter, but it is also cleaner, layered and it does well to provide a unified approach to navigating Android, and soon all of Google's services. When you add in the justification of UI elements, visual tactility present in buttons, tiles and even scroll bars, all tying in with the lighter justification of the Roboto font, it all adds up to a much more pleasant to look at UI.
I must say, ART in this implementation is
far snappier than anything I have ever experienced on the current Dalvik runtime, or the corresponding ART runtime found in the current builds of Android. Honestly, it's close to a night and day difference. Google weren't kidding with their performance improvements.
I haven't run it long enough to gauge how efficient it is on power, but it doesn't seem to be excessive. The battery bar is a bit inaccurate in terms of what it defines your usage time left to be (normally quotes me an hour or so on 90% battery life), but that may just be a bug in this dev build.
Overall- for a development build, it's very stable. I would go so far as to call it a beta build, and it is good enough to use as a daily driver for some. A few small tweaks, a larger rollout of the Material-designed apps, and compatibility with more apps, and this will be very welcome come Q3.
I have a feeling that this will be officially launched with a new device, probably a tablet. Here's hoping
