It was genuinely impressive to me as someone who loved the source material, and I have no doubt he’d put just as much work into mastering Spike if not more if given that chance.
He looked absolutely nothing like the animated character, yet Lakeith Stanfield had the mannerisms and speech pattern down pat.
Stanfield looked to be the only person who watched the Death Note anime in that film, or at least the only one who used it to influence his performance.