Also a welcome from me John!
BTW, I don't know if you know, but we (Myce) were the first to reveal details on the Tegra K1 chip, the first to know the codename of the Nexus 9 (Volantis/Flounder) and the first to report about the Android Lollipop debug icon (pretty much confirming it would be called Lollipop). By saying that, I want to underline I've been watching Google a lot
I've also been running the Android L Preview since June this year and I have to say I never want to back to Kitkat anymore. The new design (even including the new boot animation) is awesome and I've become incredibly used to the fact that the most far right button gives me easily access to all apps and web apps I've opened.
It also have a nice power saving mode, if my phone has only 15% battery left (you can change that to another percentage or turn it off) it will go in power saving mode. It will considerably slow down the phone, but still good for calls and Whatsapp and it will make the phone last much longer. E.g I know when it kicks in and I don't use it too much anymore I know I can trust the phone to last till I get home.
That feature is also excellent for Flappy Bird BTW, since it slows down the phone considerably, it's much easier to play
Given what I've spotted so far in the Android source, I think the Android L Preview brought only small changes. For the actual release I think we'll see much more impressive changes and I can't wait till I can put the next Preview on my phone today, well I hope they release a new one as they will release the Android 5.0 SDK today