Great tent. With a bit more headroom and larger or second vestibule area and a window or two, I'd give it 5 stars indeed. Ok so it's designed for weather resistance, I've not had it in a rain storm yet. I like camping according to weather locally.
Two people comfortably on one inflatable mattress, 3 maybe on individual quarters, one more and I'd have to stay in the car, I'm average build. We use a Queen sized 2 pc airbed
in here and have just enough room on either side and at foot of bed to maneuver.
An absolute cinch to pitch or strike. Like a dream. Lightweight enough for me for a short backpack trip (only one strap on cover bag though).
This tent took the place of a returned Kelty Mantra7, and I am fully satisfied with it.
I would like to see out though when animals come snorting and stampeding by at 2am and stop nearby...somewhere, oh and what exactly were they running FROM? Search me, a good rain fly seems not to include a visual ability, rather to keep you from the elements. No problems with the fly and ventilation. This Casa 6 breathes very well, so in temps below 50's, better have a warm bag to sleep in. Cleans easily and sweeps out just fine when you hold the tub floor down a tad. Zippers, so far so good.
All in all, you have 2 poles serving 6 purposes with the 3 way hubs. You place tent, put shock corded poles in place as a frame, you clip tent to frame, place fly when time comes using same frame pole ends. Remove pole end from grommet and place fly grommet over end and tent grommet and return to ground or fly grommets. So simple it's a dream to set up.

This tent is pretty damn cool, and I definitely stayed mostly dry throughout the gnarliest rainstorm I've ever seen in Utah's high Uintas. That said, one side of the tent did collapse briefly under the weight of some ice/snow mixture whose weight was increased by the constant rain. The problem is that the front of the tent does not drain all that well, it pools and then runs off all at once, resulting in a slightly startling phwooooop when the water hits the ground.

Setup is easy, once you figure out how the pole goes, and the vestibule is a nice size and keeps everything dry. The floor did not leak one little bit during the aforementioned rainstorm, and I had no condensation problems whatsoever, even in heavy rain.

As far as size goes, it would be comfortable with three people on pads, I was with my girlfriend, and it was a nice size for the two of us car camping with car camping pads and bags and duffels and whatnot. The peak height is somewhat misleading, as it is only that high right at the door, and then it slopes down as you go back. Very comfortable for my 6'5" frame, but definitely not a stand in the middle kind of tent.

Overall, I definitely recommend this tent, it is constructed incredibly well, and is very comfortable to sleep in. The fly could use a small redesign, but it only became a problem when the snow came, which isn't necessarily three season weather, so I don't hold it against Mountain Hardwear's designers. Great tent, possibly a little expensive for what it is, but I stayed dry as could be, and that's worth it to me. I'm sure I would not have been as comfortable or as dry in my Kelty tent, the seam sealing and attention to detail is where this tent excels.