Kristhian Morales’s review published on Letterboxd:
Not exactly a case of style over substance, but the characters are so simplistic and the moral predicaments so black and white that it kind of dulls Luc Besson's stylish flights of fancy. The professional hitman of the title is a morally ambiguous character in concept, but 10 mins into the film any discomfort that can arise from having said character take care of a young girl is put to rest. Gary Oldman chews so much scenery in The Professional, I'm surprised he didn't chip a tooth and leave bite marks on the film stock. Jean Reno thankfully decides to go in the opposite direction, remaining subdued and collected as the titular assassin, while Natalie Portman does her best with Mathilda, the little girl whose family is murdered at the outset. It's not really a great performance, but she gets to curse a lot and smoke cigarettes so it looks like a breakout role, even if it's all external.
Besson is a little too enamored with the "cinema du look" for my taste, but there are small moments in The Professional that remain memorable: repeated cuts to an episode of Transformers on TV amidst all the chaos or a game of Hollywood charades that emphasizes how we shape our lives based on the pop culture we consume. Even Leon, a cold blooded assassin, can trace his roots to the stoicism of John Wayne, albeit with a twist of 90s European flavor. Besson's Achilles heel in this movie is that he either confused sentimentality for substance or he set out to make a purposefully teary action movie. I sincerely don't know what's worst. The movie has a European sensibility, but the excessive firepower, the two-dimensional characters, and the emotionally pat ending are all recognizably American.
*Note: I believe the version I watched is the American theatrical cut, which excludes footage that Besson wanted in the film, but didn't test well with audiences and was later restored in an extended version.