Played a little bit of this game and yeah it looks lovely on PS4 but so far, nothing in terms of looks has beaten Infamous: SS for me (open world games that is). To think that game released so quickly after the PS4 launched, we have seen how GG have progressed since Shadowfall so cannot wait to see what Sucker Punch have managed to do next. Yoshida even said he played their latest game so chances are that by latest next E3, we will get a first look at the game.
Batman is the second prettiest open world game I've seen on PS4 though, not a mean feat at all for a game which would of course not take full advantage of the console by virtue of being a multiplatform title.
Rainfall is a million times better on Batman. I'd say that and amount of detail in any given place is probably the only things that technically beat Infamous SS, but those combined with the art style make it a better looking game to me. Oh, and I think character models are much more consistently great on AK, too. Oh, and water (not puddles on the ground, but the water out at bay). Oh, and LOD pop-in is WAY better on AK.
Sorry, I keep thinking of more things that AK does better, lol. Particles are going to be a close one, but AK might be better there, too.