It's a really good way to get a good overview of the field, and what some of the problems have been already solved in bioinformatics. It's definitely best to combine it with a more traditional textbook such as "Introduction to Computational Biology" (Haubold and Wiehe) or "Biological Sequence Analysis" (Mitchison, Krogh, Durbin, and Eddy).
Hope that helps!
Rosalind is a great way of improving your knowledge of biology and CS. It is quite cool to see computer science and mathematics problems and techniques applied to bioinformatics.
I think I have a new hobby!
But here's the rub: if you want to learn "bioinformatics", you're going to have to accept that most of the work is inherently not visual. I worked in about the most shiny, graphical part of biology possible (protein structure), and maybe only 20% of the work involved spinning molecules on a screen.
The real work of bioinformatics involves thinking very hard about problems that are deeply mathematical. The visualization part is strictly secondary -- though it gets the most attention, for obvious reasons.