Samsung Ashouldn't even ature page up, shows the ATIV S has the same Pentile display as the Galaxy S III | WMPoweruser
They use the same Super AMOLED HD screen. You can look at the Ativ S spec sheet yourself, the article above links to it and talks about the screen.
The iPhone (the single best selling phone) not having expandable storage and most people not caring is a fact, not my opinion. The only people who care about expandable storage on phones with 16 or 32 GB of memory are tech enthusiasts.
I never said it was 100% the worst. What I said was that if screen size, expandable storage, or a removable battery were ultra important to you, then the Ativ S is best. I just don't think that it is best for the average consumer. The fact that threads like this one suggesting that there are unannounced features or that Samsung has a surprise up its sleeve with this phone shows that most people are disappointed with it as it is and want something more from it.
People who have heard the amp on the HTC 8X in action have had positive things to say about it (including wpcentral), suggesting it is "a crappy dollar store level amp" is pure speculation, not based on actually released specs and early hands on experiences.
As to what else it offers over the Ativ S, here are my OPINIONS:
1. HTC has historically had better fit and finish with a superior, more premium feel
2. HTC has historically had superior manufacturer specific apps
3. HTC's dedicated imaging chip will likely lead to faster camera performance
4. HTC has had a better update history on both Android and Windows Phone than Samsung