I picked mine up today. I came here specifically to post my review. I read this site every day and I rarely post here.
First, let's start with the AT&T store experience. I went to a local store in Austin, TX. A bunch of people were waiting outside. They let us in and there was a couple who was there to see the Focus S as well. There was a display for it, but no phone on display. The couple asked if they could see it and one of the reps went in the back and looked. She came out and said they didn't have it, that they only had the Focus Flash. Since I overheard, I confirmed this with her when the couple left. She said I could wait around to check again and find out if another store had it. When my turn came up, I asked the (different) rep and she went to look in the back. She came out with one and said there were only 2 in the back (Two!).
Shame on AT&T and Samsung. What a pathetic "launch day" for the device. No device on display, no knowledgeable reps, no advertisements. There were no posters in the store hyping the device, either. This is partly why WP7 is not doing better.
Now, onto the device.
Overall, it feels good in the hand. It is very similar to a GSII, if you have had an opportunity to hold that device. I have taken sample shots with the camera and they turned out like the ones my GSII took. Very sharp and full of detail. I'm going to take some comparison shots with my iPhone 4s today and compare them side-by-side. Without the battery, the device felt very cheap and light. This doesn't deter me at all and it's trademark Samsung, but don't be surprised when you hold one.
One thing that alarms me a little is that it seems to lag a bit. It's definitely not as responsive as I expected. There is a microscopic delay when typing and when scrolling up and down, there's a barely perceptible lag to the transitions. I wish I had my original Focus with me to compare, but I don't remember WP7 ever being like that. I have been using an iPhone 4s for weeks and maybe the speed of that device is what makes it seem laggy. I will need to do more testing to be sure. All I can tell you is that the screen and camera are great. My one concern is how the phone runs at this point. I will do more testing in the coming days and post my impressions here.