I'm upset that I hadn't gotten this earlier. It's a great attachment for the cost. It is easily removable/attachable. Has two insulated drink-holding compartments. Center box with cover is great for keys, phone, etc. I used to put those things in the under-compartment, but now it's closer to my hands. The only thing is that when you pull out something that is stuck in the cup holder it pulls the whole thing up. Not a problem if you use appropriately sized cups :)
I ordered this online and my husband put it together. It took about 30 minutes to attach to the back of our single BOB stroller. My 3yo likes it so far, but we haven't used it that much (baby's not here yet). The stroller still folds up nicely. When you don't want to use the stroller board, it lifts up and gets attached by a strap to the stroller's handlebar so that it's more out of the way (but not completely out of the way). It seems sturdy with skateboard wheels (so I presume they are replaceable if you run them down). I didn't think it was the most amazing solution considering it comes out far so I'm worried I'll kick it with my toes if I'm walking and not paying attention. Value: can't complain.. it beats buying a double stroller thats tough to push around.