We have two of those coops, hooked together at the ends of the runs to create an "L" shaped larger run. We have 7 hens (3 RIR and 4 BR), so 3 roost in one coop, and 4 in the other. 5 can fit on one roost, but it is a tight squeeze. As it is for the 4, and I make sure that it's four that like each other, otherwise there is a small amount of pecking and squabbling. The two mean girls and one friend overnight in the other coop, and even then there is some squabbling. We put remote control battery operated lights inside, so once they're all in, I turn the lights off and then everyone is quiet and nice.
I was surprised at the sturdiness of these coops. We had a couple of pretty good wind storms with 50 mph gusts and a good amount of rain, and I thought for sure the coops would be flattened or blown apart, or leaky. But everyone stayed warm, dry, and secure.
Our coop is inside a small fenced yard that is between our house and our pasture, which is nice because we have an electric fence for the horses on the pasture side. (No critters are going to access our yard from the pasture without hitting that hotwire.) Our hens are allowed to roam the yard during the day. I wouldn't keep 4 hens locked in this coop/run all day every day, I think it is too small for that. We do let them "free range" outside the yard if we're outside with them, and we lock them in the coop/run if we are going to be away from home and not return until after dark. It's been secure and safe.
For ventilation, we bought some 6" vents, drilled two 1" holes below the peak of the roof, and covered the holes with the vents. It's easy enough to remove the vents to add more holes...I'm thinking we'll add two more holes under each vent as it gets warmer.
I rarely bother with the slide out trays anymore. I do wish they were deeper. I use a good amount of pine shavings for bedding, and it makes it difficult to slide the tray out without all the shavings being pushed out to the run below.
I don't regret buying these coops at all, and they are working for us in our situation. But I have been thinking about adding a rooster to our group, and I won't do it unless and until we get a larger coop set up. Even though our girls are allowed outside during the day, I still feel like we are pushing the limit on size.
**EDIT** The roosting bars are way too small for full grown hens. We had to modify them.