This sequel is by far the worst of the original OMEN trilogy. After the revelations of the first film (that all those "accidental" deaths were engineered by Satan to protect his son on Earth, Damien), there are no new surprises in the second movie; hence, there is no story. The audience already knows all there is to know, and is forced to sit and watch while a new batch of hapless characters slowly come to realize that Damien (now a teenager played by Jonathan Scott-Thomas) is really the Antichrist. Of course, they realize too late to do anything about it, and the film ends with Damien still alive and kicking and ready for the next sequel.
With no plot, all that is left is for the film to invent a new series of graphic deaths to inflict on Satan's victims: one gets smashed by an eighteen-wheeler truck; another is bisected by an elevator cable, and so on. The closest thing we see to innovation is the presence of a black crow that seems to foreshadow imminent demise at every turn.
For reasons of its own, the screenplay breaks continuity with the original. Despite the clear implication of the ending of THE OMEN, Damien has not been adopted by the President of the United States; instead, he is ensconced in the home of his uncle (played by William Holden, who passed on playing the Gregory Peck role in the first film). Also, despite his sinister smile into the camera during the final fadeout of the first film, Damien here seems to have no idea who or what he is.
At least this last idea leads to one marginally interesting scene, wherein Damien, having learned the truth about himself, runs out onto a pier and screams "Why me?" as the sun sets over the quiet water. Whether he is talking to God or the Devil, he receives no reply.
Unfortunately, this concept is abandoned almost as soon as it is introduced, and from that point on the film evinces a problem that the original managed to skirt: namely, what is the nature of Evil, and what would it do if unleashed on the world? DAMIEN: THE OMEN II has no answer to this metaphysical question, so it simply ignores it altogether, relying on the gruesome violence to sate audience appetite for horror.
Whether deliberate or not, the choice of Stanley Mann to write the screenplay appears to be a form of payback. Mann came up with the idea for THEATRE OF BLOOD (1973), one of several early '70s movies starring Vincent Price that featured plots that were mostly excuses to string together an elaborate series of creative deaths. (In THEATRE OF BLOOD, all the murders were inspired by the plays of Shakespeare.) THE OMEN, of course, borrowed this approach and turned it into mainstream box office gold.
It may be stretching a point to note that Ian Hendry, who co-starred with Price in THEATRE OF BLOOD, has a small role in DAMIEN. Hendry was also in the old AVENGERS television series, before Patrick Macnee took over. Coincidentally, one of the early victims in this film is played by actress Elizabeth Shepherd, who co-starred with Vincent Price in TOMB OF LIGIEA and also shot a few episodes of THE AVENGERS as Miss Emma Peel, before the producers decided to recast the role with Diana Rigg.