The mattress is comfortable but I will review again when I've had it longer, as a previous memory foam mattress, (not Dormeo), lost its memory fairly quickly. I was surprised at the instructions to turn it every 4 weeks which makes me slightly suspicious, this is why I have only awarded 4 stars.
 
The mattress is 20 cms deep, 5 cms less than my previous one which is just ok and actually makes stretching the sheet and electric blanket over easier. Please check before you buy as some Dormeo mattresses are only 14 cms, much too thin in my opinion. 

I didn't purchase this from Dormeo, as after after checking their site I found the same mattress for £90 less from Wayfair. Delivery from Wayfair was with me in about 3 days and well packaged. It was ready for sleeping on almost immediately after unpacking and I didn't notice any smell.