Well, maybe not exactly "terrible", but not very good at all. It's nicely photographed, and Yvonne Monlaur--a French actress playing a Chinese girl--is hot, but those are pretty much the film's only good points. Everything else is subpar at best. Christopher Lee tries hard as the villainous leader of the murderous Red Dragon Tong, but he is sorely miscast, as is pretty much everyone else. The Chinese characters are, with a few exceptions, played by white British actors, and not played very well. The "hero", Geoffrey Toone, is stiff, dull and unconvincing and seems to be standing around waiting to be told what to do. There are a few perfunctory and poorly done fight scenes--although there's a somewhat better brawl on the docks at the end--and the script is predictable, anemic and lifeless. Many of the characters, especially Toone's Capt. Sale, act just plain stupidly--for instance, the Tong breaks into Sale's home and murders his daughter, then later sneaks into his home again and tries to murder him, but he takes no measures to protect himself (doesn't carry a gun, doesn't ask for police protection, when he hears a knock on the door he opens it without trying to see who it is first, etc.). The pace is leaden, thanks to Anthony Bushell's uninspired direction--it was his third and last film as a director, and I can see why it was his last--and the acting ranges from over-the-top ham (especially when the British actors try doing what they think are Chinese accents) to under-the-top inept.
Overall, despite a few small--VERY small--pluses, it's really not worth your time.
Overall, despite a few small--VERY small--pluses, it's really not worth your time.