Having been riding for several years but never needing panniers until recently I was a bit apprehensive about these as they seemed far cheaper than competing products. I went ahead and ordered them though, and first of all I must commend Ghostbikes on their speedy delivery, I was surprised to get these a mere two days after ordering.
I bought these for a 1988 Honda Bros 400 and fitment was a trial-and-error process. Because of the universal nature of the panniers, the instructions are quite generic, along the lines of "put these straps over or under the frame, or use the additional straps around frame or luggage fitment points" etc. After an hour or so I had a good stable pannier attached, though the Bros is quite a small bike and I was left with a relatively small amount of space on which to sit, but that is an issue of my bike, not of the panniers. In fact, it speaks positively of the panniers as they're small enough to fit on small bikes but large enough to qualify for bigger bikes.
I haven't yet done extensive touring with the panniers, but after a short 20 mile ride with about 4kg in each pannier I can report that they're stable and stay in one place, and don't flop about when riding. Courtesy of the English weather I was able to try out the waterproof covers too, which seemed to hold up well in a brief shower, not sure I'd trust them in a monsoon though!
The reason these panniers did not get 5 stars is that the semi-rigid pieces which fit in the outside-most pockets of the panniers (which are provided in several colours to match whatever bike you may be riding) do not fit into the pockets and must be trimmed down. The other issue as previously mentioned is the trial-and-error fitment of these bags, but I guess that's to be expected with a universal product such as this.
All in all a great product at a great price. They may be first time panniers, but I have no doubt they serve their purpose well enough as a long-term luggage solution!