So: 5 stars for the unit minus one for now and annoying terminals = 4 stars.
Still, I can only give a full recommendation to buy here because the bubbled water tastes really great.
Addendum:
After the terminals were so bad that the unit was virtually inoperable, I decided to call at SodaStream (positive: Freephone). Then came a return receipt with which the unit was sent back to SodaStream. There, the water bubbler was repaired and now works without clamps or creak super easy.
Great service!