If I could give stars for each category, I'd give the bar clamps 3 stars, the C clamps 4 stars, and the spring clamps 5 stars.
The construction of the bar clamps is fairly solid and they work as designed. The rubber pieces are somewhat flimsy and each area that potentially contacts your work piece is about the size of a 25 cent coin. More expensive ones with pistol grips would overcome the awkwardness of tightening the handle while trying to keep the clamp in place. Saying that they "quickly tighten and release from the work piece" is exaggerated by current standards, especially when you would not want these to contact the work piece without scrap pieces in between.
The C clamps are of good quality. They are much better made than some of the cheap ones out there. I can't see anything I'd fault compared to other traditional C clamps. There are C clamps that go on and off quickly, as their bar clamps claim to do, so I can't say that these are my ideal choice for C clamps. But they are perfectly fine traditional C clamps.
The spring clamps are nice. The pieces at the tip pivot well and conform to the item being clamped better than other spring clamps I've used. The tension is appropriate for each size.
I bought the set for about $13 with shipping. For the price, the C clamps and spring clamps are better than I expected. The bar clamps are at least as good as I expected and will be good to have for the times that I am short on bar clamps. At twice the price, I would not have been jumping up and down, but I would not have felt ripped off. I can't see how anybody could reasonably expect anything better for a set in this price range.