Sorry for the late first impression, I was late for work and JUST got home (finally!).
Samsung Galaxy SIII
Pebble Blue
16GB
OK, so at first power up, it was a little slow connecting to their network...which scared me...but after first connection, it was great.
The phone is f-ing fast. Blazing. Coming from the Galaxy Nexus (it was stolen) and the fact that I felt like this might not be a true "upgrade" from that, I was really worried and frustrated with paying so much for the phone....but I don't regret it. The screen to screen response is better, the fluidity is better, the overall response is just better. I couldn't really force it to lag, though I didn't try REALLY hard.
The screen is epic. It looks so vivid and crisp its unreal. Haven't watched any movies or anything yet, but pictures and everything look great. Colors, brightness, I really dig it.
Touchwiz was one of the things that scared me. I bought the Nexus One when it came out and then bought the Galaxy Nexus next. I've pretty much ALWAYS used stock Android (N1 was my first Android phone) even when rooted...I always stick to ROMs that are lean stock, I don't like crazy heavy modding. So, like I said, I was iffy about using Touchwiz. Let me tell you, in my opinion, I'm really enjoying it. The layout and how it works in general is really really nice. Its a really neat change of pace from stock Android. The fact that I'm still learning and adjusting to it, and the fact that I'm really enjoying it already and not getting frustrated with it leads me to believe it'll only get better.
I haven't really taken any pictures yet, but I did play with the camera app and it appears to be pretty stellar and solid.
The sound......wow, the sound is awesome. I was extremely disappointed in the sound quality of the Galaxy Nexus. I basically had to "cup" my hand behind the back speaker while watching Netflix in order to kind of hear what was going on. Also, I had a really hard time hearing while on the phone (and I have really good hearing) but the SIII is amazing. The sound is so loud but crisp, in my opinion. I watched a Youtube video and it sounded so awesome. I haven't listened to any music yet on it, but I'm pretty confident it will also be quality.
Connection has been solid so far. Wifi connects right away. Haven't had any drops as of yet. Can't complain here.
Battery life seems pretty solid. This is another area I obviously cannot fully comment on because I only charged it for like 5 minutes before work after coming directly from T-Mobile. I played with it a lot (XDA, Facebook and just touching the beautiful screen lol) and the phone was at like 60% still. Not sure what it started at though...but it seems really solid to me.
The build, to me, is solid. I heard complaints about it feeling "cheap" or whatever, but I think it feels really light weight but solid. I have no complaint about the build, personally.
The dedicated home button, to me, is useless. I NEVER use the home feature on any of my phones, I always use "back" to back out of the apps completely so they don't run in the background. Its nothing bad to me, though, and for the people that are worried about the "purple" color....it literally looks like it blends in with the screen. It doesn't really look purple.
My ONLY gripe, and its not a fair one in my opinion, is the screen size for handling (width). Its a bit big for me, but to be fair I have small hands *shrugs*. The Galaxy Nexus felt absolutely perfect in my hand. I could reach anything and everything without adjusting the phone in my one hand. The SIII take some moving to reach the top portion, especially the top left, while handling with one hand. That's more my problem then it is the phones though, lol.
So, in a nutshell, this is my first impression. No buyers remorse and I'm going to spend a few good hours now getting to know my new love interest (the wife will understand). Hope it helps some of you guys out. If you want to know anything in particular, feel free to ask