Don't pass this one up just because it's not aluminum! This thing is pretty solid and should last longer than you own your house. Before you buy this, check that your rafters are 16"-on-center: the rough opening is 30" wide X 60" long. If you're an ambitious do-it-yourselfer, this should be a pretty easy project.
Ideally, you should have 2 people to get it installed (one in the attic, one down below). However, you can probably do it by yourself if you have a second way out of your attic. My technique was to first shove the 75lb ladder unit up into the attic. Then I climbed down and screwed 2X6's across the underside of the rough opening. I went back into the attic and slid the ladder over until it dropped down into the rough opening (and was resting on the 2X6's). At this point, it's perfectly flush with the ceiling below so I shimmed it square and screwed the frame into the rough opening. Last I pull off the 2X6 blocking and finish the install as directed. Bam. Done.
One thing to be aware of, this unit has zero insulation. I put mine in the garage and didn't care, but if you're installing this inside your living area, you'll need to make arrangements to insulate it. Also, it has no fire rating ... the bottom skin is 1/8" plywood. I'm a bit paranoid so I'm going to secure some 5/8" drywall onto the underside.
My huge complaint, and the reason it gets 4 stars instead of 5 ... their packaging is horrible!! Mine was shipped via UPS and it arrived looking like it got hit by a train. The thin cardboard was crushed right down to the product. UPS actually splintered the lowest tread on the ladder and I had to glue that part back together (I didn't discover that damage till I was in the last step of installation). Secondly, the hardware & instruction baggie was taped to the OUTSIDE of the box!?!?! It's nothing short of a miracle those parts arrived with the ladder.