Well, everyone's opinion of what a 'game changer' is differs, but I think it's clearly a big step-up from existing portable devices in terms of power. The OLED screen is significant though, no doubt. The clarity of the image on it is slightly disturbing when you first see it.. it reminded me of when I first saw the Sony XEL-1 display. Fantastic colour reproduction and viewing angles, and - most importantly - no ghosting at all.
I've not held one of the final form factor kits in my hands yet.. as they're not in circulation yet. I do think what initial titles have shown of rear touch panel usage is pretty impressive. Even with the current development kit form factor, the use of the rear touch panel in Uncharted feels very natural, and it side-steps what I dislike most about action-based gaming (shooters, racing games etc) on my iPhone - that the use of touch controls can end up with your hands/fingers covering a massive chunk of the screen.
So yeah, I like it.
Dean