These balls are certainly not the worst of the various plastic balls I've tried, however they are slightly disappointing in terms of durability and roundness in my opinion. After training with them for a week or so they rarely lasted without breaking, especially when you miss-timed the ball and struck the top of the blade they would break immediately. These balls do have a seam and play very differently to the seamless balls. Quite often these balls were certainly not up to the hardness you would expect for a 3* ball, the seam is hard but the rest of the outside of them tended to be quite soft.
Having said that the have a better flight and feeling than some of the other brands of plastic ball such as Joola. Overall these balls are not fantastic, but I believe the production of the plastic balls will only improve with time and the quality will get better as companies make improvements.