They are fine if you want them
The plus side is they look big, especially with opposing slides.
Personally I don't like the low ceilings in the room I'm going to spend most of my awake time in. I also don't like how the kitchen is completely separate and below since my wife likes to watch the boob tube while cooking or doing stuff. The areas feel very separate.
You can get rear living units that are just as big, still have the high ceilings and retain a separate living kitchen area without closing the two off to each other.
I think there are better floor plans.