I'm interested in seeing how he's going to handle his new character.
It'll be neat to see how he uses his new character.
ーI'm interested in seeing how he's going to handle his new character.
「彼が新しいキャラをどのように使いこなすか興味がありますね」
I'm interested in ... で「…に興味がある」
to handle で「使いこなす」
ーIt'll be neat to see how he uses his new character.
「彼がどのように新しいキャラを使うかを見るのは面白いですね」
It'll be neat to see ... で「…を見るのは面白い・素晴らしい」
ご参考まで!