Casting

I love Ray Milland and Farley Granger, but despite their professionalism they were both wrong for their respective roles. Harry Thaw was such an unpleasant "baby-faced" misanthrope, somebody as likable as Farley Granger, despite his 'baby-face' similarity, could never capture the monster that that man was, despite Granger's masterful thespian skills. And the real Stanford White resembled Wyatt Earp (with his over-sized mustache) more than the matinee idol Ray Milland. Moreover, the script made nothing of White's sleazy obsession with underage beauties, focusing more on his avuncular nature. White had successfully seduced Evelyn when she was 16 and his obsession only lasted for a year so by the time she was 17 he'd moved on, unaware that Thaw was on his case.
All in all, the real story is far too demented to portray realistically on the 1955 screen. The movie was beautifully produced and well acted. But anyone interested in historical truth would be terribly misled by the film. Thankfully they omitted the story of Evelyn's holiday with Thaw in an Austrian castle which is so sordid as to defy belief as to why she would marry him in the first place, despite his wealth. The real characters were much less innocent than this silly mistelling. However. it's a fun movie, despite its inaccuracies. That turn-of-the-century dance-girl show was beautifully filmed.
A more realistic retelling of this story is far overdue. As a matter of fact, the sordid nature behind the lines would be well suited for the over-indulgent contemporary tastes of today's audiences. In fact, it's as sick as the real story behind "In Cold Blood."