Ignore the moronic and juvenile posts from above that were more about making the poster feel superior than answering your question. But this is ./, I wasn't surprised.
I've had my Samsung Gear 2 since July, and find the following functions the most useful, in no specific order. Most smart watches have similar functions, the camera probably being the one that is the missing from many of them.
1. Telling time (duh)
2. Timer. Something I use a lot more than I thought I would because it's easier to use and I don't have to take my phone out of my pocket.
3. Camera. Picture resolution isn't that great, but it's good enough to document things and share on Facebook (which I don't post from the watch, I post from my phone. Might be a way to do it from the watch, just not that much of a facebook fan that I care.) Don't expect to print 8x10 glossy pictures though. After having one, I wouldn't get another smart watch without one, it's so quick and easy to use and always easily available.
4. Get text messages. You can send them, but it's either by voice which can be annoying to others, or some of the keyboards. Keeping it to short 'yes/no' type 1replies are possible, carrying on a conversation about where to go for dinner and why .. probably not.
5. Send and take phone calls. As long as someone is in your contacts, the voice recognition works pretty well. The comments I've had from my wife is the quality of the audio on her end is pretty good. Because the speaker and microphone is on your wrist, it can be difficult to hear or hold it comfortably to talk. I had a conversation from about 50 feet away from my phone when I left it inside my car at Home Depot and was in the contractor bay.
7. Get other notifications. This can drive you nuts, unless you are one of those people that insists on being plugged in constantly. I turned off the email/news notifications, just got too many. Other people that I know that have one use it for those things.
8. Calculator. Tiny buttons, good for quick calculations.
10. Store customer cards. I have loaded the bar codes for most of my loyalty cards, makes it easier in some stores with remote readers, useless in others. Since it doesn't care what the bar code is, might be useful in a clean room if you have to scan bar codes.
11. 'Look behind'. This is an app that lets you see what your phone camera sees. Great for looking under sinks and behind furniture. Probably not very useful in a clean room.
12. 'Find my phone'. Easier than finding another phone to call your phone when it's lost.
13. I like the square look more than the round look, makes more sense for a computer screen.
Caveats:
1. It's not a platform to spend long amounts of time reading. The screen is small, and even with support, my arm gets tired after using it too much to read the news and other things.
2. I have to charge it up every couple of days. Because it uses a proprietary cradle, you can't just plug it in to a USB cable to charge it. But .. it's also water and dust resistant, that's the price you pay for those features. I set the display brightness low, which extends the timing.
3. Fitness programs (i.e. pedometers) chew up the battery life. If you want a fitness watch, get one. If you aren't interested in tracking those types of things, this watch is fine.
4. Don't even start to believe you are going to type emails on this. The face is just too small for anything other than very small text messages.
5. While the watch band is replaceable, finding one that fits can be problematic. I haven't spent a lot of time, but because of the way the watch is designed, I think one really needs to go to a store to find one rather than online. I've tried a couple around the house from old watches, and the ones that fit looked like crap. But .. it doesn't require any tools to remove, although the same may or not be true for the one you replace it with.
6. It's a PIA at night driving or really doing anything at night. It keeps coming one when driving, and if I'm sitting on the patio enjoying a drink with my wife at night, it comes on every time I reach for my beer. There is a way to lock it off, but it also turns off notifications. Wish that was an easier thing to do.
So basically, the great thing about it is that it interfaces to your phone so you don't have to take your phone out of your pocket for some things. I would never buy a smart watch that wasn't tethered to my phone, I will always carry both.
I read an article bemoaning what watches had become. I realized the article was wrong. This isn't a watch, it's a wearable computer. Watches have been passe for years and will continue to be worn more as a fashion statement than something very useful.
As I said above, I've had it for about 6 months now. I'm pretty rough on it, I don't take it off to mix mortar or dig trenches and stuff around the house, so I've put it through a lot. So far, no scratches on the face and the rest of it is holding up really well.
I'd buy another one.
I've had many people ask about it, and they all thought it was cool. I haven't met anyone that thought I was a glasshole, because I'm not rude when using it.
As for the Apple watch .. meh. I like the crown thing on the Apple watch and the way it charges, the Samsung cradle can be a pain. Most of the app differences are relatively minor and will probably be seen on Android once developers get their hands on it. It doesn't have a camera option, which I think is just stupid now that I've used one with a camera. I really didn't see anything that makes me think one is that much better than the other, so I guess it's just a matter if you would rather be locked into Apple or Samsung. Or go with one of the other generic Android watches and lock into Android.
And if you want one now, you really don't have a choice. Apple is still giving generic responses to release dates