The original Back to the Future became a justifiable smash hit and so the demand rose for a sequel. In this instance, Robert Zemeckis was wise to return to write and direct, it was a case of 'come back, or we'll get someone else to do it' and so rather than have the original turn into a Jaws or Superman series of diminishing returns, the sequels built upon the original in clever and often inspired ways. The second film is usually deemed the least successful as it doesn't have quite the lightness of tone of the original, isn't as much fun as the third and the plot is loopy and paradoxical. It it is all explained quite clearly, the viewer just has to have their brain engaged, which will come as a shock to some. Coupled with that, the darkness of the alternate 1985 setting isn't quite as appealing as the innocence of the 1950's in the original, but Zemeckis has great fun with the time travel paradoxes and the cliff hanger ending is genius.
Although heaped with praise, Alan Silvestri's original Back to the Future score rarely escapes the bonds of its terrific main theme and occasional, but admittedly successful secondary motifs. Much of the action is percussive and a fraction uninteresting, Silvestri never quite manages to pull the whole thing together. To some extent, the same is true of the sequel, although it does show a slightly matured composer - one who'd manage to produce the terrific Who Framed Roger Rabbit? in between - and while much of the original material is revisited, the whole experience feels that bit more cohesive. In the pantheon of the sequel scores, this is firmly in the 'more of the same, but better' camp. It's not hard to be thrilled every time the immortal main theme appears and gives the heroic punctuation that the darker material needs, notably during Hoverboard Chase and Tunnel Chase. Admittedly, these two are actually well conceived generally, with ticking string motifs, the obligatory brass hits, percussion and even a Goldsmithian piano obbligato.
Some of the central passages are pretty low key and uneventful and Silvestri only just about manages to keep the ball rolling with an effectively sustained doom laden atmosphere. Despite Varese's Back to the Future Trilogy compilation album, I don't think many people will be happy until a full release of the original score is released, although so much of the material is reprised that this album makes for an adequate alternative. For my money, a more extensive selection of highlights from all three films would probably be a better alternative to the original albums anyway as none of them quite sustain their running time. If Back to the Future II lacks the freshness of the original or the thematic variety of the follow up, it still functions as a passable sci-fi, adventure score even if one can't help wondering whether some of it would register without such a terrific main theme.