OK, so I've played a bit with the S4 (i9505), so far, really not impressed...
Looks a little more stylish because of the metal looking plastic frame and it's a bit less rounded.
Other than that, screen is fine, but I've not found my old S3 being much worse. Difference in resolution, not noticed, so no big deal for me.
I'm not into benching, but what the heck, I threw an Antutu over it, and guess what ...
--> RANDOM REBOOT
Damn, I mean that thing is full stock, booted first time, just completed Google sign-in, installed 1 user-app and I get a random reboot as welcome ?!
OK, rebooted, went to the app drawer to rerun Antutu, app drawer lags ?! Seriously ??
Antutu went through this time, scored a nice 25655, not bad at all, but in using the thing, not much of a difference, probably only if you're into hard gaming.
Conclusion so far, thanx, but no thanx (and I could get it for free for work !).
Might get me a Note II instead
JP.