I have an Eglu Cube and it has been an excellent coop. I have four large chickens and they have plenty of room in the coop, enclosed run and fenced in pen. We also let our girls out during the day to roam the yard and this has been a perfect combination of space and safety.
I have had no problems with the roosting floor or the nesting area and the girls seem quite content. The great part about the Eglu system is that the roosting and nesting area are super easy to access and to clean, so every day I can take just a minute or two and clean out poop, quickly replace soiled bedding and give the roosting bars a quick rinse with the hose.
We have not had any problems with ventilation at all. During the hot summer nights, the enclosed pen is very sturdy and provides excellent safety/protection from predators so the coop door can be left open. In winter it has been warm and dry.
All in all, the Eglu coops seem to be very well thought out, functional and they are well constructed. Like any new set up, it will take you some time to make additions and modifications to suit your yard, birds and climate, but the Eglu coop will give you a good start.
There are lots of helpful reviews and stories online about how people have been using their Eglu coops - I found those super helpful!
Good luck!