Sorry, but that is utter balderdash.
The navigation software on them is iGo Primo, which is VERY high-end. It has loads more features than any other software on the consumer market.
It is very definitely not a standard sat-nav with added weights and dimensions. It's the software used in some high-end Blaupunkt and some other satnav systems, often "skinned" to conceal the iGo branding.
However, it is not designed to be intuitive: you really do need to read the user guide to use it properly. And they are often supplied with no user guide, but with defective configuration and missing files in the map data set: that's why you need to get the latest mapping update from the Facebook group.
As for letting you down when trying to find a site, please explain what way it let you down. By failing to work? By taking you to the wrong place? By taking a wrong route?
The Nozatec hardware is definitely low budget: it does cost only about £40 retail (I've never seen it as expensive as £50). The quality control can be iffy ay that price point, but if you get a duff one, send it back for a refund and buy another!