From the Eitech kit I recently bought, I've built the fist model. Quite fun, and looks good. It was not difficult to put together, however it took some time getting used to the different pieces. Also, there were some very small places one had to get to in order to put on the nuts. Finally, the instructions could have been a bit more elaborate at some points. Or rather, they could have included more steps. By doing too many things at once, the pictures sometimes became a bit confusing and unclear. The instructions contained 16 steps to build this car. If it had been a Lego model, it would probably have been three times that number, for the same number of parts.

Here's some building and finished pictures.