The Moto films were 'cheaps', made quickly and inexpensively, and also rather short to pack in with other films for a cinema experience packed with a variety of films in a string. Where most other films of the time have either risen to heights through brilliance or, as most have done, fallen from interest completely due to mediocre or lackluster efforts, the Moto films have found quite an enthusiastic audience that still thrills to the honest, entertaining portrayal of an exotic crime fighter.
Mysterious Mr. Moto is the first film in the series where the crew seems to have 'gotten it together'. The acting, acing, story, and film work were all quite a notch above the previous three. Though the stories are always rather linear they keep an audience by balancing thrills, violence, mystery, character and mild romance.
The criticism of racism is odd. Lorre plays the character slightly off Japanese, his accent being obviously Germanic, but his mannerisms are keen. Moto is an American schooled Japanese, which was very typical in those days, and it gives him an obvious bridge in understanding western culture. It is a pity they didn't find more Asians to fill key roles in these films, but generally the American actors used were quite good despite looking too Caucasian. I can forgive authenticity for acting ability, especially in the days when there were few stories written for Asians.
Moto always comes off as a powerhouse. He's an admirable figure for anyone undersized in a brutal world. Kids must have loved Moto in the day as he proved someone tiny could trash giant brutes with guns and ham hock fists. He's a great roll model for more than just Asians or Japanese, he's a hero for everyone. These films are fun, matinée film that portrayed the shrinking world with a metropolitan and international flavor. I think they are admirable. Lorre proved himself adept beyond any doubt with these movies. They are a credit to the entire crew.