On reading the other reviews, I was cautiously optimistic about this mattress. Most complaints were about the expansion of the mattress and a chemical smell so, I will consolidate the advice I found in the reviews coupled with my own experience to ensure the reader knows how to get the most out of this excellent product. First, when you unwrap it, be careful not to cut the mattress or mattress cover, but only the box and plastic shipping bag. Next, remove the mattress cover in a well-ventilated room. Open a window if you can. Let the mattress expand for 48+ hours on a hard, flat surface, flipping it over after the first 24 hours. If any corner does not raise or seems crunched up, beat on it, fluff it, massage it, knead it, etc. until the corner is expanded and full. The chemical smell went away for us because we let it lay out for so long. Once the mattress is fully expanded, put it back in the mattress cover, pop on a sheet and place it in your crib. We have two Graco Lauren Convertible Cribs and the mattress fit in both snugly and with ease. There was no space left between the crib slats and the mattress after about ten minutes of settling. Check my pictures out for an idea of how nice the fit is. The final measurements of the mattress are: 52"x28"x5". So, in short, the other negative reviews complained of a smell, failure to expand properly and an ill-fit. By removing the cover and letting it expand/air out for 48 hours, this is all alleviated. With foam, you are ALWAYS going to have a heat diffusion issue to some extent due to the properties of the material, but other than that, I will take that any day of the week instead of a noisy, uncomfortable mattress. My newborn son is already sleeping well on his new foam mattress so don't be put off by folks who didn't take the time to get their mattress in the best possible shape. Good luck!