To be fair it's electricity, reviews don't really matter as far as i'm concerned.
It does when they take multiple payments, don't answer calls/emails which is what many of their negative reviews say. They were also in the news recently for threatening action against customers who had left negative reviews.
I emailed them two weeks ago because their website has virtually no information about the switching process for smart meters and never got a response, so not exactly a good first impression there either.