The knock on Fu Manchu is that it's basically racism on a stick. The knock from the movies is that it is racism on a stick and they didn't even have the balls to get a real asian to be Fu Manchu. In this version we have the always great Christopher Lee. Now Lee's great and all, but it's distracting noticing how not asian he is no matter how much make up they trowled on.
Once you get past that part, Fu Manchu basically plays like turn of the century James Bond. Nayland Smith is Bond and Fu is the Bond villain with the extravagant plan. In this case he's working on a device that basically is a death ray and working on how to hypnotize as many pretty ladies as he can. When not doing that he keeps himself amused by feeding people to the snakes. Nayland doesn't bed near as many ladies as Bond and is more of a detective trying to find where Fu's secret base is. There's a lot of derring do and action and swashes buckled and of course at the end Fu makes his escape as his lair is compromised.
So if I was going to redo this puppy, how would I go about it? Well first, of course, I would make sure we had an asian playing Fu. In this day of age with hong kong cinema it shouldn't be hard to find someone to fit the bill. Now I'd love Jet Li to do it as a counter to his usual role as a hero, but I realize maybe he wouldn't go for it.
The next thing is a rewrite of the character. Now we don't need to get all PC and all, what we need is context. Perhaps give Fu stronger ties to chinese organize crime like the triads would help. In fact, what I think I would do is give Fu the back story that he was strong in the triads and then broke away. This gives background in the criminal element and sets him up as a very strong figure. It also gives Nayland an unlikely ally as the Triad never forget or forgive a betrayal.
From there things fairly write themselves. Play up the turn of the century James Bond elements. Kick up the action. I'd certainly would like to use exotic locations. Actually it would save costs in some respects as there are parts of the world that still look nearly as they did at the turn of the century, something a little harder to achieve in London.