It took me about 15-20 days to get used to it. I developed a backache initially, but my physio friend told me it’s because I am not used to having my back straight for long and I have posture issues due to prolonged sitting on PC chair. The issues got resolved and I am pretty satisfied with it.
I didn’t opt for memory foam and other options primarily because I sometimes sit on my mattress and work, so a sturdy/firm surface was more suitable for me. If that wasn’t a requirement, I would be getting something from the latex product range. 100% latex mattresses are pricey, so I would get something that has a layer of latex which would help in Delhi summers.