The best thing is: you can get a big sleeping bag for two person, or two single sleeping bags, all in one!
I was looking for sleeping bag because I was planing a Yorkshire 3 Peaks hiking with my girlfriend. Our accommodation was an inn which needs us to bring our own bedding. So we need a sleeping bag for 2 people.
And this one is exactly what I need: it can be a big sleeping bag which just suitable for a 1.8m width double bed, or 2 small bags for 1m width single bed. The thing is the portability: It's extra huge. But if it's divided into two, they will be much smaller, that we can carry one individually.
About the heat preservation, to be brief, it far more enough to use in a room at Yorkshire countryside in November without a working heater (the first night). And it's too warm when the heater is on (the second night)... So I guess it would be also enough to use outdoor in a tent in the same weather.
In conclusion, it's not your cup of tea if you are a experienced hiker seeking lightweight equipment for long distance multiple days hiking. But it will be your first choice if you are with your partner planning a self-driving tour, camping, travel with indoor accommodation, or short distance 2 days hiking.
This sleeping bag helps me a lot recently. On weekend my friend brought her twins children and her mother to my home. I have no extra bed for her and her children ,nor extra quilt. And by chance school asks for a list including sleeping bag. So happily I bought this .And this is a good buy. My friend said very good for they three , and big enough for two adults and a child in. Warm enough in my lounge .