Uluru is basically a huge rock in the middle of a dessert. It is so spesial because it look like a mountain in size, but is in fact a rock! It is also very very red, just to make it even more strange.
For the aboriginals it is a holy stone, that have a lot of history behind it. So even if you still are alount to climb on it if the weather allowes, everyone ask you not to. This would be very offencive for the aboriginals, it would be like climbing on top of a church or something.
Anyway, Uluru is definitely a must do! It was absolutely amazing! You should see the sunrise and sunset as well as take a walk along the stone edge and have some tours with guides to learn more. Just so much to do at such a amazing place!