The blurb on the back:

Here, unearthed from the old records in the basement of the New York Police Department's headquarters, is perhaps one of the most exciting and unusual chronicles of the world's most celebrated detectives - Sherlock Holmes. But it is written not by Dr Watson - but by Theodore Roosevelt, destined to become President of the United States.
There can be no doubt that Holmes visited America before he met Dr Watson - and that he helped solve a most violent and devious crime there. A crime that proved to be one of the most taxing of his brilliant career - and with the aid of Roosevelt himself...

opening lines:
By no definition had I ever considered myself a serious student of the life, times, case and adventures of Mr Sherlock Holmes of 221-B Baker Street.

Badly written, pointlessly plotted and utterly, utterly unnecessary. Apart from that, there are no redeeming features: it's just a fifth-rate historical crime novel hijacking Holmes because otherwise it wouldn't have got published.