I have a 15" MBP, 2 160 GB iPod classics, Apple TV, 1TB Time Capsule, wireless keyboard, wireless trackpad, iPad 1 and other Apple goodies so I was/am firmly entrenched in the Apple ecosystem. I switched to a SGS3 about 7 weeks ago from a iPhone 4S, I do not feel in anyway disconnected from the collective hive, I prefer my new phone and am still able to sync all the things I did before with my 4S, albeit with a bit of setting up at the beginning, which was simpler than I imagined. Would I go back to an Apple phone? Not at the moment, my setup works for me, I will of course look at the new iPhone but TBH and IMHO, it will have to be really spectacular to upstage my S3. I'm hoping it is.
I was really worried before I switched, that worry was unfounded.