When United decided to nickel and dime us all with baggage fees (and we almost got slammed with an overweight fee), these looked like good choices. We got two. They arrived quickly. Each weighs around 4 lbs. which is pretty darn light. Also, while they are your basic black, they have yellow markings that help distinguish them on the carousels. I have NO idea how waterproof they are.
The capacity is huge, and the tethers inside do a respectable job holding everything in place. There are a couple of outside zipper pockets, and for something like a down comforter it does have an expandable top. HOWEVER . . .
. . . I still have NO clue what the criss-cross straps are on the top/outside do, since there's no way to attach them for any support, and the velcro handles are goofy and have separated just about every trip (you'd see this on the baggage carousel..). In addition, I guess some "baggage handlers" must have tossed one of them, or set it under other stuff: the back end (where the wheels are and a support post) apparently cracked into multiple pieces, no longer serves its intended purpose, and looks like it can not be fixed.
Finally, a good feature is that the bottom is where the metal trolley arms collapse into, so there is a relatively 'firm' bottom. That allows you to pack some things like smaller artwork and the like that needs to be flat. Just remember to put a couple of things above and below as a cushion. I would NOT recommend these bags for ANYTHING you might consider fragile.