So some more thoughts:

1) The Samsung supplied headphones produce a nasty glitch when pressing the inline buttons. Seriously, did anyone think to try this or they did and just thought: "yeah sure, that's good enough...". Not quite as bad as my HTC HD2's inability to play its intro tune without skipping though.

2) The power button is a bit awkwardly placed relative to the volume buttons on the opposite side. When I want to press it to lock it, I naturally grab it on either side which means pressing the volume up as well. When at my office desk that's particularly a pain since it turns the sound back on (I have Tasker set it to vibrate when I enter work's Wifi range). Can probably get used to but it's not intuitive to lock.

3) iPhones have had the headphone port on the top ever since always. The SGS III is the same. My HTC HD2 is on the bottom. When I put my SGS III in my pants pocket that means it's the right way up with the headphone cable at the top. But when I grab it, I grab it by the top and so pulling it out means I'm holding it by the top. So I have to rotate it in my hand. With the HD2 I just pull it out by the base and I'm holding it in the right location.

4) Pressing the home button takes what I consider an unreasonable amount of time to hide the current app and show the home screen. Probably my biggest gripe at the moment.

5) Face unlock works quite well but takes a bit long to turn the camera on (need to try it with a photo but I don't really use it for security) as does the Smart Stay face detection.

6) Direct call is a nice feature once you remember you have it.

7) Battery life isn't bad on the second charge. I hope it gets a bit better though. A fullish day with a fair bit of data gets me to about 40%. Would always like more and will buy an extended battery if made available.

8) The wide screen is almost too wide. The keys like Q and P on the onscreen keyboard take a bit of getting used to.

9) It noticeably lags on some things already. I didn't expect this.

10) The Samsung apps don't intrude really.

11) S Voice is a gimmick like Siri and for some reason only works on 3G and doesn't work on my home network. I haven't investigated why yet though.

12) Sliders for things like answering the phone or snoozing/turning off reminders are a bit unintuitive to look at whilst sliding. The sliders don't move with your finger. They just disappear and an outer ring lights when you've slid far enough.

Some of these first few are simple usability/use case things but I do find it a bit hard to believe these situations are out of the ordinary and I'm the only one who thinks this?