How would you measure experience? The amount of years one has been programming is obviously not a good criterion, what this thread shows quite well. Looking at the written code is already much more promising.
A lot of people just want to develop their game and see C++ as a tool to achieve it as fast as possible. They had better use a different language, because C++ is absolutely merciless when you don't know it well. However, when you are interested in the language itself, it will be much easier to gain experience. It may sound boring for some people, but the impact on the written code is tremendous -- when knowing modern C++ techniques, life becomes much easier. It took me a few years to realize this, too. Although it requires some time and motivation, I think it is important to keep reading (good books and article series from C++ experts), even more since C++11 is a more and more present topic that inherently affects the code style.
Some older statements of mine related to the topic, in order to avoid repetition again and again:
And don't underestimate the importance of good C++ knowledge. By "good", I mean you know concepts like RAII, type erasure, functionals or templates. You understand why new/delete should be reduced to a minimum, and how STL components (containers, iterators, algorithms) interact with each other. How to decide between static and dynamic polymorphism. What other possibilities of abstractions exist in C++. Why you should avoid global variables where possible. And so on... The reason why this knowledge is crucial, even if advanced, is because it determines your everyday programming. You write code in a completely different way if you do not understand those topics -- usually, code is more complex and error-prone, harder to maintain and less efficient. You will see how much more fun it makes to maintain a project with a well-designed code base (and also how completely frustrating it is to spend days of debugging because of bad code).
In C++, there are several problems. Modern C++ techniques have only come in the 2000's with authors like Meyers, Sutter, Alexandrescu. And at the moment we are only seeing the first practical implications of C++11 being more and more supported. People interested in the language experience progress first, it takes a while until the "average developer" learns new idioms.
A second problem is the vast amount of terrible literature for C++. Many books have taught an antiquated C++ style, close to the beginnings at "C with classes". The same is true for C++ libraries, it is not easy to find a well-designed API as in SFML, especially in the field of game development. Inheritance overusage was, and still is, a big problem. Not only in C++ -- take a look at the Java standard library, especially the collections. Java has fewer abstraction tools than C++ -- in C++ they often were not used, although available.
I believe that this "not-usage" is not only a result of small practical experience, as many experienced people (in terms of finished projects) still don't use modern C++. It is rather also a consequence of the difficulty to find good articles or books, which in turn is due to the complexity of C++ and the slow spread of knowledge in the community. A lot of techniques can't be learned only by programming, thus I find it important to read about them, and to try to apply them in projects, beginning with the first project.
