I like Im's reveal, I personally don't understand the criticism. Cool powers, interesting apparent weakness to the lower realm and he buffs the other guys.
Early chapters of Elbaf were not good, starting off in a dollhouse for... what reason again? I forgot... probably because the reason sucked. And it wasn't nice to learn that the giants gave up on being warriors and are officially bums.
But now we have a legitimate threat on the island, plus Gaban got a very cool chapter injuring Im. Obviously admirals aren't going to cut it as world government villains anymore so this was a natural progression.
Would be nice to see giants do something though, they are getting the samurai treatment in that they were hyped as game breaking soldiers but it turns out they're just mid apart from Loki.