From my little experience with Unity, it is easier than it looks. It tooks me few afternoons to learn (Unity 3 xP). The great things are the market and the large community. You can find tons of ready to use addons to work with.

But I would say that the most important thing is not the tool but the understanding of how the tool works internally and that is not easy to research. It is hardly explained.

Learning to draw properly drawn models is not an easy task too. From my experience there is no way to build a consistent looking game with bought assets. You need a solid knowledge of the rendering pipeline to be able to glue the assets from different artists. Same as for drawing.

Acknex is cool but it is hard to build a modern looking game with it. Needlees to say that you need to learn tons of things to control the rendering, but it is same with Unity. Once you know all this stuff it is far easier to swap from one engine to an other.

Salud!

pd: Thank you @all for your consideration towards non-German speakers.