Overall, very little. I’ve had this phone for about six months now and I love it. Tablet? Nah, don’t really need one. Either I’m mobile, in which case this is enough, or I’m able to sit down at a proper computer with a keyboard and a large screen.

However, familiarity has made a few design flaws and weaknesses apparent so, on the offchance that someone from Samsung is reading, here’s what I’ve found.

• Worst flaw: placing the power and volume controls at the same level on opposite sides of the case. When you want to press one, it’s natural to try to brace the device with a finger on the opposite side of the case, which usually causes you to press the other button as well or instead. I can’t believe nobody from Samsung bothered to pick the phone up and try this at any point. This is the single biggest annoyance, and requires conscious thought to work around.
  Added to which, it’s difficult to pick up or hold the device while active without hitting something unintentionally, whether it’s one of the side buttons or the virtual buttons on the lower part. When I have a call, which fortunately happens rarely (I don’t actually need the phone part a great deal), I have a 50% success rate in pulling it from my pocket without cutting off the caller. It’s almost impossible to remove from the Samsung car dock without either pressing buttons or releasing the whole cradle. My kids have great difficulty using it without losing the app they want by accidentally pressing the menu or back key. (Btw, Famigo is a great sandbox app to limit the amount of trouble they can get into while playing games.)
• Volume control: The volume button controls the ringer volume. Except when you’re in a game or media app, when it controls the media volume. But if you want to adjust the media volume ahead of launching something that may be noisy (i.e. while on the apps or home screens), you’re out of luck - either launch a music player and do it there or go to Settings.
  Also, every time I plug a cable into the headphone socket, I have to increase the media volume back to max. In some ways, this is a feature as the volume seems to magically reset itself after removing the cable, so you don’t get accidentally blasted later - but I don’t understand how and under what circumstances it does this. The media volume level is a constant mystery. Anyway, why should I have to adjust the volume when connecting to an auxiliary input? The whole point of a line-out connection is that it’s a constant, fixed level.
• Size: In two minds on this. I once read that Steve Jobs judged the iPhone screen size to be optimal, based on the reach of the average thumb, and I can see his point. It’s sometimes hard to stretch your thumb across to the furthest reaches of the Samsung screen, especially without accidentally touching an area lower down (like the Back key). On the other hand, that large screen is gorgeous when you’re actually looking at something. No larger though; might as well pack a tablet then.
• Bloat: If you’re going to pack the phone with pre-installed bumph, at least give the customer the option of disabling or uninstalling it. I still have a boatload of Samsung app-related tasks running (such as Ap Mobile, Yahoo! Finance and Social Hub) that I never use. I really wonder how much better the battery life would be if this stuff could be stopped permanently.
• Stability: It’s very good but yes, Android is noticeably less stable than iOS typically is. So far, I’ve seen the phone hang while preparing the camera (requiring battery removal), hang and refuse to let me acknowledge while receiving an incoming call and spontaneously reboot a number of times (usually after many days of uptime). Not a showstopper, but suggestive of deep-seated and obscure bugs lingering.
• Upgrade path: We’re getting ICS, great! I’m not betting on receiving the next major Android release after that though, based on Samsung’s past record. On the other hand, at least we have Cyanogenmod available; my 2nd gen iPod Touch was obsoleted by Apple as I have no way to access the security fixes post iOS 4.2.