This mattress has been very comfortable so far. We've probably only spent 10 nights on it but it is comfortable, firm with just a tiny amount of give/softness that your body sinks into. It really is a firm mattress though, if you or another person sleeping in the bed like plush or even soft, don't get the firm one. We're not sure that it actually fully expands to 12", it's more like 10"-10.5" (reason for 4 stars). We opened it and let it rise for 48+ hours before laying or sleeping on it but that's as big as it got. Otherwise, the mattress is great!