Astarion is the best companion we have so far. I kinda dislike his attribute changes that were introduced in the last patch but he is still the best.
Astarion is the worst companion of them all as he is completely lore breaking. A Vampire Spawn without any of the characteristics and powers he should have and also without most of his weaknesses. And just saying "its the tadpole" is a very weak excuse.
I think he was talking about the character's personality. Also in my party Astarion is one of the most powerful characters (if we speak about skills). He also has a bite that helps a lot(and reminds you that he's a vampire, besides water). For other abilities, perhaps too early? I think he should get something else at level 5.