i'll second that. Make sure you don't hang from it with your hands too far in or you will bend it. I can hang from it with a backpack full of weight as long as my hands are far out enough. There are other types of bars as well. Mine was about 20 dollars at a local sporting goods stoor.
I am studying abroad this semester so I decided to bring one with me. It's been a great help. I can do pull ups whenever I feel like it. It will probably get the job done if you just want a bar to do normal pull ups on.
If you put it in your doorway, it is likely that you might be a little cramped for room. I put mine in the small hallway going from my door.