My wife had been pestering me to get the new "spinner" style luggage that she had seen people using at the airports. As an engineer, I looked at the design of any of the spinner type and realized that the design had two main limitations
1. The wheels are smaller and thus more difficult to roll across rough surfaces. They might work acceptably on glass smooth floors like you see in many airports, but there is going to be noticeable resistance when going across carpet, sidewalk, or road.
2. Because you are pushing on an extended handle, the moment arm of the force applied makes the luggage more likely to tilt over. As such, you need to push with less force which causes you to go through the airports slower. If you want to go faster, you need to tilt the luggage on two wheels and drag it behind you like traditional wheeled luggage.
But, she insisted that she wanted the new style luggage and this was cheap enough that it would make for a cheap lesson for her, so I bought the set. She has taken one trip since I got the luggage and has come to realize that I was right in my initial evaluation of the spinner design. As such, it was entirely worth the cost to me since seldom can a man spend that little money and get a woman to tell him that he was right. :)
I think that the luggage would be more stable when moving through the airport if it had a provision for hooking a leash to the bottom so that you were pulling from the bottom and not from the top. All it would need is a pair of rings on each piece of luggage on opposite sides near the bottom that you could attach a snap bolt attached to a leash (like you see with dog leashes). You could also have very short leashes with a snap bolt on each end to attach the luggage to each other so that you could drag your "train" of luggage through the airport.
I purchased the yellow colored model, so that it would be easier to see when it came off the luggage carousel at the baggage claim area of the airport. My wife says that this has helped quite a bit. Most luggage is black and it's often difficult to quickly distinguish your luggage from someone else's as it comes around the conveyor belt. The only thing is that the yellow is a bit lighter than the yellow in the photo.
The main complaint that my wife has is that the material that the dividers for each side is made out of seems too cheaply made for her. It's basically a plastic material like a lightweight plastic tarp. The liner zipper was broken, but I was eventually able to kind of fix it as long as she only operates it from one direction. I've never been impressed with plastic zippers and this is yet another confirmation of my prejudice against them.
Only the smallest of the three pieces actually meets the size requirements for carry-on luggage due to the space wasted by the wheels. If the wheels were easily detachable, the medium one could probably fit in the overhead bin on the aircraft though. They don't look easily detachable though.
Even though the luggage seems smaller than her existing TravelPro carry-on bag, she is able to put just as much stuff in it. I think it might be slightly thicker which makes up for the decreased height of the smallest bag.
To make the bags more stable when you are pulling them in 4 wheel mode, you probably should consider putting your heaviest items at what will be the bottom of the bag when it is standing up (i.e. near the wheels).
One thing that I noticed on her recent trip that used the medium bag was that she had loaded it fairly heavily and when I picked it up by the side handle to put it in the car, the handle "felt funny". The listing had said that it had a "padded handle" to make it more comfortable, but the padding is a soft rubber and it kind of rolls under your hand when you have a bit of weight in the bag. I have to think that this padding is not going to last and will eventually come unglued. I would have much preferred a solid feeling handle.
The exterior zipper is plastic and I have already mentioned my distrust for plastic zippers. No zipper is that secure, but a heavy duty brass or steel one is definitely better than a plastic one and would only have added a couple of bucks to the manufacturing cost of the luggage. With this type of luggage, you have to consider the fact that if the zipper breaks and you did not properly secure your items in each half of the luggage, you are going to end up with all of your items dumped out. It would be nice if there was a secondary clasping mechanism around the perimeter of the luggage in case the zipper burst open. Baggage handlers are rough on luggage and it is not unreasonable to assume that eventually there might be a failure when they are tossing your luggage around. I have some 1" nylon strap that is about the same color as these bags and I will be making up some straps that can go around the luggage for a secondary method of securing the closure of the two halves. I would highly recommend adding a luggage strap to this style of zipper closure luggage -- preferably two straps (one in each direction).