This thing just survived a month-long camping trip to France during which it never failed. It worked in scorching hot conditions at times and although it did get warm to touch it worked fine throughout. Essential for keeping the coolbox going. The 12v socket part does seem a little insubstantial but it survived being thrown around a bit and if you hold the actual socket, not the lead, when you're unplugging it's all fine.
The device supplied to me was actually a Kampa device, which is sold under various guises by numerous sellers on amazon. It might be worth checking the different prices offered.