I didn't like the mattress at all, they are just too old. And this is a serious problem. A suggestion for improvement: adding some spare plates apart from a set for two people would make a difference :) When traveling with a kid we had to share between three people what was arranged for two only. Same with armchair at the table, only for two. A stool from a bathroom would solve the problem, if there was any. Also limited number of utensils in the kitchenette, so required some virtuosity when preparing a dinner. Small issues, but would be a bit disturbing for a longer stay.
Our room was warm enough even we stayed alone in the big house for the first night. The bathroom clean and arranged in a smart way - I'd add only a small stool for practical use. Hot water all the time. Flat TV set on the wall, even though with Russian programs only. Wi-fi in a room without a problem. A playground for kids! Parking for free. A nice, big reception hall.