The good thing in this chapter was that the fight with the Sea God finally ended (I was getting sick with the fact that for the past 8 months only few steos were between Guts and the conlusion of the arc, even frontlines in WW I moved faster than that), the far less pleasant thing is that Guts won because of the... Singing? WTF?! What will be coming up after this? In the next fight will he win because in the crucial moment poor orphaned children will tell him that they belive in him? I didn't have anything against Isma and i even like her (she was funny and in a far better way than the absurd elves) but that bunch of other mermaids coming out of nowhere, reunion with the child that lost its place in the world and all that singing could be all scrapped and the story would only get better because of it.
As for Guts current situation - he just pierced a heart that pumped blood for tens-of-thousand (if not more) ton body, even if he wasn't flattened by the pressure alone he should have drowned. Before I would be wondering if he perhaps will get out of it because overuse of Berserker armor will turn him into a non-breathing undead but now I kinda suspect that one of the fish-ladies will bring him up and heal with magic born of love or sumethin'.