There are two kinds of horror. Well...arguably more. There are two major kinds of horror. There's the kind this movie was advertised as being, evidenced here (warning: trailer has no bearing on the tone of the film, and only briefly its themes):
And then there's what it really is, which isn't even really a horror film at all. After all, when your sympathies are more in line with the monster than the human protagonists...that's a very different kind of terror. Co-writer/director Vincenzo Natali is obviously reworking the Frankenstein story with the story of two bio-engineers, Clive (Adrien Brody) and Elsa (Sarah Polley), who manage to make this weird sort of almost-human creature by splicing human DNA into a compound involving DNA from something like seven or eight other animals.
And then things really get wild.
Now, when someone says a movie was "weird," they typically mean one of two things. Either it's an Alain Resnais film and they're saying that things seem to happen for no real reason, or they're saying that the film has some stuff that you don't typically see in a film. Now, yes...Splice has quite a bit of stuff you don't typically see in a film. Stuff that will certainly push a great many people past their comfort zone. The fact is, the mistakes Clive and Elsa make are not in any way limited to the actual creation of Dren, the thing that emerges from their experiment. In fact, though the film introduces the idea that doing so could be considered immoral, this basic idea is presented fairly innocently I'd say.
So, yeah, when the film starts out by positing that, eh, maybe making a creature that's partially human isn't such a bad thing, and then has its characters do horrible, horrible things...you know these are people who don't fit into the often-mandated definition of "relateable." That said, there are character- and thematically-motivated reasons for everything Clive and Elsa do, and as dark, disturbing, awkward, uncomfortable, and unconventional as the movie is, I never felt it straining to reach those points. At one point or another Clive and Elsa have to separately deal with the dual idea of Dren as a person, which they treat it as, and as what she really is - a science experiment. The moments when they decide what she is - and they flip-flop on this often - are telling and fascinating, and have just as much to say about science and ethics as they do the responsibility of parenthood.
Thankfully, most of the heavy lifting in the character department is left to Polley (as my girlfriend will tell you, I greatly dislike Adrien Brody's performance in almost every film). Polley is one of those actresses capable of almost anything, frequently turning mundane lines into divine revelations, and big moments into game-changers. I don't think I've ever seen anyone express surprise and amazement as genuinely as Polley does in a scene here, and when the film gets a little more cliched towards the end, she expresses fear as nakedly as the screen has ever displayed.
This is far from a flawless film - the plot machinations to get from one point to the next can be a tad strained, the timeline is a little questionable, and the films asks to go along for some fairly major leaps in logic. But that all falls under the category of "stuff you complain about when you don't like the movie anyway." Because everything that actually matters in the movie is spot on. The questions it asks, not just about morality in science but of the concept of "family," are things that are really worthwhile. The occasional sloppiness of the storytelling pales in comparison to the relative success of its considerable ambition.