Yes, it is. Maybe not for the begginer, but Google open source C++ stuff tend to have a great code quality.

Also, the modern open source C++ stuff from Microsoft is also great.

Go for Chrome, V8, Dart, ChakraCore, the C++ part of DotNet VM.

But the only "problem" with them, is that they use their own sort of smart pointers, but if you know that they map 1-1 to smart pointers from std:: when you need to use the std ones, its not a big deal.

Chrome for instance have scoped_ptr = unique_ptr, scoped_refptr = shared_ptr, etc..