Firstly, The Matrix is AMAZING! My friends had been telling me about it on a school trip, and I desperately wanted to see it. I bought it at a second hand shop on video, and when I saw it was 15 rated I was slightly worried, I'd never watched a 15 before. We did watch it in the end, and my worrying was for nothing. I wasn't scarred for life or anything, and there isn't anything particularly scary in it that will stop you from sleeping for weeks afterwards. There is a gross scene where the hero (Neo) has his mouth covered with a sort of sticky stuff, and then get a sort of scorpion inserted through his belly button. A kid age 10 maybe wouldn't be able to handle that, and I felt a bit sick afterwards. It's over quickly though, and there isn't anything else like that in the rest of the movie.
There is extreme violence, but it's mainly in a non-reality world where the characters don't draw blood most of the time, and you know it's not real because they float in the air and stop time and things like that. There's a lot of shooting too, but the killing is mostly off screen and there isn't any close ups of people getting shot.
One person The Oracle, who is just an old lady baking cookies, smokes. This scene only lasts about 5 minutes. Yes, there is a scene where one man drinks wine, but that only lasts for about 5 minutes too. There are no drugs or anything as far as I can remember, but there is bad language, butit only goes as far as Sh** and "Goddamn"
Anyway, I found this movie really awesome, way better than my friends were explaining. I'd give it a 10/10 if I had to rate it. :)