i know you say you don't want a screen, and i'm nto sure how much these pictures do justice but i'll show you anyways since i had them on my phone.
here is a pic projecting on the yellow wall, no flash. notice all of the color you can see on the walls and floor reflecting.
http://i.imgur.com/8se86cm.jpg
here is a pic when i had the walls painted and the screen up, also have the speakers under the front, so all of that will also help with reflections.
http://i.imgur.com/LfkaKYd.jpg
it looked badass in both scenarios to me, but with the screen and darkened walls it is a different experience because it gives you that "window" feel that you are totally focused on one thing and can't really see around it. my setup is definitely not as pronounced as many theater pictures i've seen in that regards, but it's as close as i can really get.
but all in all, projectors take it to a whole other level as you now know!