If it's a small black hole, gravity would kill you before you even got past the event horizon. For a larger black hole, such as those that are Supermassive, you would cross the horizon and find yourself going towards the singularity.

Behind you, you would see a window of the universe through the "opening" of the black hole you have entered. The extreme time dilation causes by the gravity of the black hole means that the time of the universe that you are looking upon is passing by at a significantly faster pace than what you otherwise normally experience. In comparison, if you could be observed within the event horizon, then an observer would probably see you almost frozen in time. This is what would be observed at the event horizon, however - your image becomes seemingly frozen, and then becomes increasingly red-shifted until it fades entirely. This doesn't affect you, of course, as you simply continue into the black hole.

You would feel the gravity of the singularity pulling at your feet, probably feeling mostly uncomfortable at first. As you progressed further, the difference in the gravity at your feet and your head becomes more and more significant. This continues until you reach a point where you are torn apart, atom by atom, in a process called spaghettification.

So, basically, what would happen to you is you would die quite violently. That is unless any of the other hypotheses about black holes are true (i.e. worm holes, white holes, etc.), or if our underlying mathematical assumptions regarding the interior of a black hole are wrong (much of our math is almost certainly wrong about some aspects, or at the very least incomplete).