Our daughter loves this bed, and she's just 3 and a half.  The Rails are a bit low even with a 10" standard twin mattress, so we had to add a standard bedrail to the length and it was fine.  The bed is quite solid once built up, but probably just for the kids.  The build quality is "ok" -- on our unit the ladder pieces were not cut properly, and holes were on the wrong edge.  The dresser included had drawers that slid off the rails (very low cost rail mechanism, not gliders).   Thankfully wayfair customer service is top notch, and they shipped out replacement units quickly.  I anticipate this lasting her 3-5 years.