Amazing! I recently bought the queen size (which is adjustable to king and California king). It is super sturdy; it was easy to assemble (I am short and not particularly handy),  and it doesn't not require any tools.  The first night I slept on it, I noticed a huge difference in the firmness and support of my mattress. I think the middle cross bar with three support "feet" is the reason. My partner is twice my size and also commented on the incredible change in support. I do not regret buying it and I would recommend it without hesitation.