Im loving it so far too.
What I like:
The screen looks fantastic. I've read a lot of people complain that it isn't as crisp or HD like as the One X or other phones, but I think it looks awesome and clear.
The feel of the phone is small and light, fits well in my hand. The hardware is great. Reminds me of my Nexus One
The audio is actually really loud when you turn up the volume. Much much louder than my Nexus One.
The camera is great! I love that there is no lag between taking pictures. You can take pictures while you are recording.
I'm actually fine with not having an SD card. I had everything backed up on my computer anyways, just plugged in the One S, and restored things. It did take longer than it should, but what else can you do. I think 10gm of phone storage and 2+gb of internal storage is good for me. (We'll see what I say in 2 years)
As TurboRanger91 said the car dock is much much better than the gingerbread version. It actually makes me want to try it. Normally I would just open up the "Navigation" app and use that instead but I may use the car dock now.
It's super fast, and the battery has not lasted me all day, but that is because I have been playing on it all the time, doing things that would normally drain the battery. So I haven't been able to see how it is under my normal use, and not my "I have a new phone going to play with it all day" use...
What I don't care for:
I have had a few times where the phone resets itself. I think it is because one of the apps that I have isn't quite compatible with 4.0.
The location of the usb port. I'm used to having it on the bottom of the phone rather than the side.
The notification light is so dang small and only blinks green, and only blinks for a few minutes. I would like to be able to change the color for certain notifications and for it to stay on until I dismiss it.
Having trouble keeping the WiFi on. It keeps wanting to disconnect on me. I've found a few "solutions" but they didn't work out for me.
I agree on the T-Mobile logo on the phone... I hate it.