I bought this set having found my usual straight 4mm hook, the one I used most often, was hurting my hand, The hooks themselves are of sturdy-feeling plastic and the case is very nice. The rubber grips are also and added bonus.
However there are some downsides, hence the low rating.
1) the head of the 4mm hook broke after a couple of weeks
2) the rubber grip of the 5mm, the next most used, started to expand and come unstuck, making it uncomfortable to use, and the head of this one broke recently too.
All in all not bad for comfy hooks but not good for high tension work like amigurumi or prolonged use. Get something with a steel or aluminium head instead.