Anyone who says you can "fully learn" C++ is either a liar or doesn't know what he's talking about. Usually both. Do not believe anyone who says you can truly know all of it.
What makes it so hard to *master* C++ is that it's extremely expressive. No one fully knows everything there is to know about C++, save for its creator and, possibly but unlikely, a few other gurus. C++ is extremely complex(and I don't mean "using it"). Most people who program in it don't know or use half its features or possibly more, because you don't usually need them. It has a plethora of features, and I, although having years of experience programming in C++, can't say I know or use all of them.
At first you think you know C++ just because you can use its classes and such, then you realize you're not using 10% of its potential. C++ is pretty easily a paradigm by itself.
I know a lot of languages, from Prolog to some I wrote myself. C, C++ and x86 Asm language are the ones I use the most, but I won't dare say I have mastered C++ even after more than 7 years working with it, simply because it wouldn't be true. However, I'm "fluent" in C++ and can safely say I can use it to do whatever I require.
It's not hard to use C++ to write software, just like it's not hard to use English to express myself. But have you ever seen anyone using English to its fullest? C++ is like any real language. You can hardly say you know everything there is to know about English. There is always something you don't know, and knowing it would open a world of new ways to express the things you usually say, but differently. Or, better yet, C++ is like Japanese: you can spend your whole life studying it but will never know everything there is to know about it.
It should take you about a month to know its basic rules. In fact, you can use any language in about a week(to a certain extent, of course), specially if you have experience with other languages. But C++ is quite different from Visual Basic, mainly the part where you actually write programs instead of editing them. Simply put: C++ is much more powerful than VB; there is no comparison.
But, as I always say: if you want to be a good programmer, learn Mathematics.