I have to say - I don't like 52 all that much. I find it long and boring. I, for example, skip a lot of the plots (the Elongated Man/Fate storyline, the Question storyline) and one of the ones I skip is the Black Adam one. So, to be honest, I didn't really care that Kid Black Adam died, nor did I care that Sobek killed him.
However - I think the scene where Sobek goes from helpful pet to crippled child murderer is a very good scene. It IS powerful, shocking, and harsh. If it can have a positive effect on me (in that I go, "****! He ate him! Savage.") and I haven't even been reading the damn story, I think it's hardly gratuitous. I think it's the right choice. Off planel as we see Sobek munching as little blobs of blood pop out would've been too, "Oh - he just ate him". The savagery would've been lost and I think that was key.
But I could be wrong - it could be totally inappropriate considering what's come before. As I say, I've not been reading 52.