You may have seen the previews for it. I was under the impression it was a horror movie, and by horror I mean plot-less gorefest because that's what most contemporary horror movies are. I was expecting to heavily dislike the movie, namely because I hate horror movies, and I only went because all the friends I was hanging out with were going to see it, and also there was nothing else good playing. I didn't have a hankering to see Letters to Juliet, Sex and the City 2, or Shrek Forever After.
So I went and saw Splice. And holy crap. It was not a horror movie. At least not until the last 10 or 20 minutes. It's about these two biochemists/genetic engineers- who happen to be lovers- who splice various animal genes together to create organisms that can produce various proteins of use in pharmaceuticals. Against the orders of the company that funds and operates their lab, they splice animal and human DNA. And thus, Dren is born. She grows at an accelerated rate, and the scientists eventually become attached to her; the female scientist a bit before the male.
The movie is very emotionally powerful. There are some scenes that almost made me cry. And then, towards the end, it just gets freaky strange. Upon the conclusion of the movie, I was left in a state of near shock. Not horror shock. Just... I don't know how to describe it. I really really really recommend this movie, if only so you can get the true impression of it. I'm not going to go into plot details, the movie is rated R.
If you can stand to see a movie that plays with your emotions, attaches you to a character, and then goes and effs stuff up- in a way I don't want to describe only to protect integrity of the plot- then go see it.
If you're one to nitpick about character development or how realistic the science is or if you are constantly vigilant for any kind of plot holes, I don't know if the movie will fit your tastes. I'm not usually that picky about movies, unless they're really bad. And this was a really good movie.