1) LG G3
2) How small the bezels are, how thin it got at the edges, the display, surprisingly good battery stamina given the resolution and size of said display. How much screen you get for the general size of the device. It looks really satisfyingly futuristic, in the way you wanted stuff to look in 2014/15 in the 90s. The shiny concentric pattern on the chin, finish on the back, shape of the thing, lack of buttons on the front or sides and just all of it make it look like a scifi prop more than a lot of phones. On a negative note, the dumb software sharpening that makes everything look like an over compressed jpg once you stop staring slack jawed at the device and turn the screen on. It's a total joke.
3) The number one thing would be how slippery the phone is, and how hard it is to get a solid grip on. I rocked it caseless for quite a while(maybe a month?) and could not stop feeling like i was going to drop the thing and break it. It's so slippery it wouldn't even stay on the chair next to my bed at night while i was charging it, and slid off on to the floor over and over. Eventually i got a spigen slim armor, which made it feel almost exactly like a big nexus 5(or the nexus 6 that should have been). I installed cloudy G3, the sharpening fix, xposed, and a few other mods and really started to settle in to the phone. The battery life remained good, but i started to notice a lot of situations in which the camera really sucked. It's great probably 80% of the time, but it's either great or awful with no middle ground. An example would be taking a photo of someone standing in front of a lit christmas tree. It ended up a noisy mess with massively blown out highlights. In comparison, an old iphone 5 knocked the shot out like it was nothing. I'd say i took 50-60 photos with the phone before i sold it, and most of them were good. The bad ones were REALLY bad though, and sucked in a way i've never experienced with an iphone. I'm aware it's well known that's a very high bar to clear, but the good shots were really good and the G3 is known for having a good camera(which it mostly does) so it was kind of surprising. As for the "laser autofocus", it works ok. When it works right it's very fast... but it's not so good that you never miss focus, or that it doesn't hunt sometimes. It's a lot like the camera itself. Very, very good in most situations, not really a value add in maybe 20% of them.
As for other parts of the phone, well the 1 watt super speaker is just... a phone speaker. It's on the back, and it's still a back facing tinny speaker. This isn't boomsound, or even a particularly great speaker. It's pretty much only good for having the loudest ringer i've heard on a phone since the ruggedized motorola PTT nextel phones for construction workers. You could hear the thing outside your house, from the front yard, if it was in the very back of the basement. Oh, and it comes with this incredibly hilarious ringtone. The screen also just... isn't that bright, and gets really bad color shift/polarizing at certain angles. It reminded me of the screen on a nice pro-grade laptop 10 or so years ago, like a thinkpad t series or a powerbook g4. It's good, but it's not up to the standard of the M8, recent iphones, Nexus 5, or anything else that's known for having a nice screen. It just does not look that great unless it's perfectly dead on if you have one of those phones in your other hand. And yes, it does get hot. It never bothered me, but it gets warmer than any other recent phone i've used in completely innocuous, normal situations. Just redditing or having a couple tabs open in chrome could make it hot. Not warm, but hot. Like a laptop.
That said, performance was mostly solid. But that's how it should be with an SD801 and 3gb of ram. I was able to leave more stuff loaded without having apps reload or chrome tabs reload on this phone than i've ever been able to on any other device, including non-android stuff like ipads. Not all the animations are 100% smooth all the time, but it feels plenty fast and there isn't much chug or jank. I'd love to see how the SD805 version performs, i bet it kicks ass.
A random thing is that it draws enough power while charging to make some crappy chargers overheat and shut down. Several chargers that i've used fine with many other phones exhibited this behavior with the G3. It was really annoying, because you'd end up with a loop of hearing the notification buzz that it started charging every couple minutes. Eventually i just started charging it with an ipad charger when i didn't have the stock LG one.
If you have really big hands, which i do, the chin can actually be small enough that it's really annoying/hard to hit the soft back button or even the home button. The buttons on the back, on the other hand, are one of the best parts of the phone. More >5in phones need to adopt this. I got used to it in maybe a day or two and i still miss it on other phones. The back volume buttons are especially nice when you're in a call, and don't have to fumble for side buttons to change it since your hand is already resting on the back anyways.
The auto brightness is REALLY stupid and continuously sets the screen too dim. It doesn't even always crank to 100% with sunlight shining straight on it, and was perpetually too dim indoors. I was constantly fighting this, and ended up leaving auto brightness off a lot of the time which IMO wastes battery compared to a good automatic setup. I'm suspicious that they did this for heat and battery reasons, but it's tiresome.
4) The IR blaster is cool, but it's the most finnicky IR blaster i've ever used on anything. It has to be pointed almost perfectly at whatever you're trying to use it with. Even my old palm pilot had a more wide angle one. It makes it feel a lot more gimmicky than an actual feature you'd use all the time. I still did, and so do a lot of other people, but it's worth noting.
The ROM scene is ok, but only really for the d855. I had the AT&T D850, so it was pretty dead and most of the roms never really made it to it. I was fine with cloudyG3 with the sharpening fix and didn't really want anything else, but if you wanted CM12 or something... meh.
Worth noting that any AOSP based rom ruins the camera. It makes it look like the really bad indoor shots i discussed all the time. It's like the camera on the G1, or the original iphone, or something. It's BAD.
Eventually i sold it to go back to <5in phones(and try out the iphone 6), but it's the only 5.5in phone i'd consider, and in my opinion the absolute limit of what you can consider a phone before it's just a phablet. Hell, we were calling phones smaller than this phablets just a couple years ago. I also think the battery life, while decent, is the absolute lowest rung of acceptable. I wouldn't have to try super hard to run the battery dead in one day. It's not the nexus 5 where it'll do that on its own, but i've owned more than a couple phones that could easily last a day and a half of hard use. It struggles with that one, for sure.