He will certainly improve but don't think he will ever be worth the money they paid for him, or be the player he was at Leverkusen. They want a KDB type impact over the next several years and I don't think he has it in him. He's technically gifted, neat and tidy, and links up well. But (and it's not like me go on about stats) I don't think he will deliver the GA that playmakers or attackers of his price generally must to be considered a statistical success.
But yes, he's easily better than he's currently showing. But don't think he's as good as the fanboys have hyped him as, never did. A bit in the middle.
I still think he can be a part of a team that wins trophies at Anfield, though. But he's a bit of a luxury signing.