The Score only gets exciting during the robbery scenes, they are staged well enough and even now look great. But the rest of the movie was boring. And to be clear, the robbery scenes in the movie are not frequent - there is one small robbery as an opening scene, and a big robbery at the end.
In between the scenes the film tries to develop its characters, and there is enough time to develop them, but the characters look cardboard, unconvincing, devoid of any raisins.
And this is in spite of the presence of star actors: there are no complaints against De Niro, he just started to grow old and this is one of his last star roles in which he appears not as an old man, but as an action hero, even though he is getting old. Norton's performance was unconvincing, largely overplaying the role of the sick man. And the bloated Brando is just for the furniture - a frankly weak role, played for the sake of royalties.
And because the characters were not interesting enough, the plot twists do not impress much, the logic and motives are at odds. And while the film shows the kind of groundwork that could elevate 'The Score' above the masses of similar films - that groundwork is not used. And 'The Score' as a whole is a fairly average film with a bunch of star actors.