It's sturdy and is not hard to assemble, being made mostly of metal.  The problem is the 6-in maximum mattress depth warning comes at the end of the assembling manual.  This critical limitation should have been disclosed in the description - basically you can't use any mattress that is taller than 6 inches due to falling risk.  Good luck finding a 6" mattress.  Here's the warnings quoted from the manual: "Ensure thickness of mattress and foundation combined is greater than 4" and that it does not exceed 6".
 Surface of mattress must be at least 5" (127mm) below the upper edge of guardrails."