Last Thursday, I installed the Android SDK. It went smoothly, I've installed it under two versions of Windows 7, as those are my systems with the most RAM and CPU power (for the Android device emulator. My older Mac and Linux systems lug a bit when doing serious hardware emulation.)
I started the online tutorials linked on the SDK's opening page. Since the SDK is based on Eclipse (my favorite full-fat IDE for Java), it was no problem getting started.
I got a simple app, modified from the 'getting started' tutorial, running on an emulated Android device within an hour or so of starting.
The next day--Friday, my phone arrived in the mail. It runs Android 4.1.1.
After a busy day on Friday interleaved with charging and moving into the phone, I got the Android SDK talking to my phone today, downloaded an updated version of the app (a =very= simple character generator for my RPG, RoonVenture.) It ran just fine. It's very similar to my online RoonVenture Character Generator.
That is, it's ugly, poorly designed, but bone-simple while producing the essential results.
Nevertheless, I found my Java skills played right into Android development (so far):
Android's native language is Java, with some unique libraries.
The default IDE is Eclipse, a common Java IDE (and one I recommend, though I still do about half my code in something lighter, ranging from vi or vim to Arachnophilia or BlueJ.)
It's a lot like Java ME development (which I've done to build apps for my older "feature phones".)
So, if you're doing Java now, I recommend jumping into Android if the opportunity arises. I've found it easier to get started than with Java ME, Blackberry, or Nokia Series 60 development. Though it's worth noting that I'm coming to this with prior experience with all of those first.
Now I'm taking a break from the computer and reading a hardcopy book, "Creating Android Applications" by Chris Haseman. It's written for the experienced Java programmer who doesn't need 250 pages on Java and Eclipse.
That should help me make a better app next. :)