I installed this on a Saturday morning, and I'm impressed!  The overhead storage rack added useful space where there was just ... space.  
The amount of storage is huge!   I was worried whether it would fit but it works perfectly,  If there is an issue, you can use fewer sections, but the full 4x8' area is awesome.  Also, it's rock-solid - the sections are secured to each other and the hanging mechanism is just like the Gladiator shelving (you can see it in the background).  
Installation:  They recommend 2 people - I agree.  I did it myself in one morning, but two people would have been helpful. 
I absolutely recommend it - the perfect place for storing Christmas stuff!