I can confirm that the original Sinclair computers were both shite, and awesome. Equally.
The concept was awesome. The manuals were amazing. The quality control was.... unknown. Literally, they didn't understand the concept.
My first Sinclair computer (a ZX spectrum+... the plus was 'plus something better than rubber keys but ONLY marginally) didn't work out of the box. Dixons diagnosed a dud power supply, and swapped it for one that only worked occasionally. Eventually my ham fisted attempts to put enough force on the connector to get the thing to start, caused the pin in the 9v connector to fall off. The second one (replacement after a screaming fit by my usually non demonstrative mother, who'd paid for it) worked flawlessly. And still works. Albeit with a few mods and a non-original PSU