Test pillows, sheets, protectors, and toppers first.
Ease of movement matters as much as softness for some sleepers.
Motion transfer can make the bed feel unsettled.
Surface feel
Some mattresses feel buoyant, some feel cushioned, and some feel flatter and more stable. Surface feel is personal. Rather than asking whether a mattress is good in general, ask whether it gives you the right mix of softness, stability, and ease of movement.
Temperature feel
Mattresses can hold warmth differently. The surface may feel warm because of foam, protectors, sheets, or heavy blankets. Before blaming the mattress alone, test lighter bedding and better airflow. If the mattress surface is still the warmest part of the bed, a breathable protector or topper change may help.
Motion and edge feel
If you share a bed, motion can matter. A bed that transfers movement may feel busy, while a bed with less motion may feel calmer. Edge feel matters if you sit on the side of the bed, sleep near the edge, or have a smaller room where the bed doubles as a sitting surface.
When replacement makes sense
A new mattress may make sense when the surface no longer gives you the comfort feel you want and smaller changes have not helped. Before replacing it, test the pillow, bedding layers, frame support, and topper situation. Large purchases should solve a clearly identified problem.