I like to sleep on a firm mattress. I recently purchased another brand of mattress that was supposed to be firm but was not. When sitting on the edge of the bed I would sink down almost to my elbows. Laying on it left me stranded on it as I sunk into it and made it difficult to move about. I had to return it. 
I am happy to say that my Brooklyn Bedding Plank Firm Luxe has lived up to its promise of being 'firm'. It offers great support and the top layer of foam offers great comfort. Additionally I wake up with noticeably less back pain. It truly is a dream to sleep on.