Most of the dial-a-weight systems I researched were also negatively reviewed. The PowerBlocks on the other hand seemed to be well reviewed except by those who initially were not using them correctly (they have to be on a flat, fairly firm service for the two sides to align while adjusting).
Once I got used to them, I’ve had no problems. I do exercises lifting and tossing them about in all directions and have never been concerned about them coming apart.
You’re paying a premium for the space saving, but I needed that.
Now if they just weren’t so damn heavy…