We love this bed with trundle, it looks so nice and sleek that it will work well for many years. We don't use the trundle as another sleeping space though I like that we have that option down the road. I bought this for my thirteen year old daughter and she uses the trundle for storage (love it). There is a pretty good space between the mattress and the side board, but my daughter uses a lot of pillows so it isn't much of a problem for her. The bed was pretty easy to put together for someone with tools and a bit of knowledge one side of the head, foot board didn't have the cover cut over the holes, but you could tell where it went to no harm (there was no swearing in putting this bed together so I would say that is a plus).
Over all I love it and my daughter loves it and would definitely suggest it to others.