Hopefully this repost of the images works. If not, check in my photo gallery here.
We definitely had some condensation inside, when we set the tipi up on wet sand, and left it overnight with no fire inside, but we burned that condensation off within 30-45 min of firing up the stove. The one day that we had heavy rain all day, we had one or two drips at a seam. I didn't bother seam-sealing before this trip. We didn't get condensation from people/gear.
We had 9 people in big camp chairs in it comfortably, and used it really for hanging out and drying out gear. It was super nice to have a warm, dry place to eat dinner and hang out in, rather than everybody going straight to their tents after dinner. I don't think anybody slept in it, though.
It's 10'-11' radius, and 10.5'-11' tall. I know that sounds funny that the dimensions are variable, but it really depends just how you set it up. You can set it up wider and shorter or taller and skinnier (a little bit each way, not a whole lot) depending on the space that's available.
I'm happy to answer any other questions.