The specs on the S3 look very good. For some reason there were alot of rumours suggesting it would blow the One X out of the water, which was a bit silly since Samsung wouldn't have time to significantly change the specs by the time HTC revealed the One X.
It looks like it could be moderately faster than the One X but it is very hard to tell at such an early stage. It will only be on the most demanding games that we might see a difference. Although with alot of the main Android games getting the Tegra 3 optimisation the One X might win out despite a slower GPU.
Personally I'm not a fan of TouchWiz. I am sure there are plenty who like it. It just seems to me than Samsung are unwilling to overhaul it despite the critism it gets.
I'm not a fan of voice control to be honest. There really aren't many situations where I would want to "talk" to my phone. For the moment it screams "gimmick". I am worried the eye-tracking could fit into this catagory too, I am also worried about what effect this might have on battery life. It is an interesting idea though, even if it fails I think Samsung should be aplauded for trying something new there.
I know there was real hope for a 720p non-pentile AMOLED screen. But I guess the tech just isn't ready yet. Personally I think the pentile screen on the Galaxy Nexus is lovely, nice blacks, if a bit oversaturated. The SLCD2 screen on the One X is very very nice though.
I can see what Samsung were trying to do with the design. They wanted it to look like an evolution of the S2. Unfortunately I think this has been their biggest misstep. The phone looks average, it just doesn't compare with the One X, One S or iPhone 4s in the looks department. I know it's not the most important thing but when I spend hundreds of pounds on a new phone I want it to look nice.
A removable battery and expandable memory are nice, alot of people didn't like that they were missing on the One X.
I will say now, I own a One X. Not because I am a HTC fan boy but because I had an opportunity to get a sim-free one for less than half price. I have tried to make this post as unbiased as possible because I think Samsung have been fantastic for the Android platform, and I do really like my fiancee's Galaxy Nexus.