I've had my S3 since release and I've had a Samsung Galaxy Tab s 10.5 since release in June 2014. As a tablet, I feel the Samsung beats the S3 hands down. For one thing, there are many, many apps in the Play store that either aren't in the Windows store or a gimped in the Windows store. Some examples (based on what I use): "White Noise" for sleeping. Works great in Android and has twice as many free sounds. On S3, as soon as the screen turns off, White Noise stops. This is because the screen turning off and going into standby mode are the same thing.
The Kindle metro app is TERRIBLE in Windows 8 (and it's been around for two years). You can't store anything local so all my eBooks I converted to Kindle format won't work unless I use the desktop application. The desktop app just isn't intuitive using the touch screen controls and it doesn't display correctly. Any images are stretched because Kindle desktop fills the screen space and you can't tell it otherwise (at least I couldn't find a way).
A good sleep timer. There is no metro app that closes down any applications you have open when going to bed. So, if I'm watching TV shows on Netflix it will keep playing episodes when the next one finishes. Or if I'm listening to a music playlist in Plex I can't shut it down with a sleep timer app. I had to create a batch file that actually closes processes via the task manger. The computer will then go into standby mode after all my possible media apps have closed.
I was forced to use my S3 exclusively when I sent my Samsung in for repair. I thought if I had to use it I would find ways to do everything I do on my Samsung. Sadly, when I got my Samsung back last week I haven't turned my S3 on. I have a laptop at work and I use my Samsung at home.
I think the S3 marketing is misleading in a way. I feel it is a far better budget laptop that can OCCASIONALLY perform as a tablet. However, this isn't the all-in-one device I was hoping for. That's too bad because the hardware itself is absolutely top-notch. I only wish they hadn't abandoned the touch cover. If you want a tablet primarily and a laptop secondary, the touch cover is much better in my opinion. It's less bulky, the keys don't move while you're holding it as a tablet, etc. An old touch cover will work, but it won't cover the whole screen and it won't put the machine into standby when folded over the screen.