1. Not for everyone

　　A useful way to express that not everyone will have interest in this topic. People have very different interests. Science, for example, attracts certain kinds of people while sports attracts another kind. Use this phrase to tell people that they might not like the popular choice. It is good for you but not good for everyone else.

　　2. The last frontier

　　In the nineteenth century, many battles were fought on American soil. Many areas of the country had yet to be discovered and the new Americans came to explore. The outer most part, furthest from the main cities, was called the "frontier". This was the boundary between settled and wild areas. So the last frontier is the last boundary that humanity must overcome.

　　3. It makes sense

　　Essentially, this is another way to tell someone that what they have said sounds right. Their logic is in order. In fact, you may even start to believe what they have said. If something "makes sense to you" then you probably agree with it.