The script of this Witness for the Prosecution manages to captivate thanks to delicious and incredibly well written dialogues, and Charles Laughton's performance who superbly delivered them and who clearly stands out within a cast that has no big flaws but isn't exceptional either. The plot however lacks sometimes a bit of interest, and the rhtyhm a bit uneven doesn't play in favor of this very static movie.
But the main point for which it can be blamed is its ending, not that the "initial" twist is bad, far from it, it's excellent, but it is followed by a series absurd and very little credible twists. The explanation for this improbable outcome lies in the Hays Code, this censorship code that governed Hollywood's productions from 1934 to 1968 and obliged Wilder and his writers to provide this rather twisted (!) ending that inevitably impacts the quality of the movie on the whole, which remains a notch below 12 Angry Men for example.
But the main point for which it can be blamed is its ending, not that the "initial" twist is bad, far from it, it's excellent, but it is followed by a series absurd and very little credible twists. The explanation for this improbable outcome lies in the Hays Code, this censorship code that governed Hollywood's productions from 1934 to 1968 and obliged Wilder and his writers to provide this rather twisted (!) ending that inevitably impacts the quality of the movie on the whole, which remains a notch below 12 Angry Men for example.