It feels like he's desperately trying to be whimsical but is awkward and unnatural at it so his performance feels super fake. If you're going to make a Wonka movie then Wonka's performance matters more than anything else.
What got me was the accent he is using. It seems to keep switching all depending on the dialogue he is giving, which I found kind of distracting but maybe it’ll be better in the actual film? Who knows, I do think he is a talented actor and I really loved the first two Paddington movies so maybe this will turn out.