As someone who is not good at reading notation, I have found my understanding of it has greatly increased as a result of learning ABC.

Apart from a few instructions to the computer, nearly everything in ABC corresponds directly to something in notation. Being able to play back what I have written to check that I have got it right is a huge help. Of course the same can be said of any music notation program, and ABC happens to be the one I use. However I believe that having to think about the musical syntax to write it out in ABC has probably given me a greater understanding than I would get from simply dragging and dropping notes onto a stave.

For me, ABC complements notation. It is a quick and easy way of writing out a tune so I can print it off as notation. It is the most efficient way of jotting down a tune on a scrap of paper when no manuscript paper is to hand. If I am struggling to make sense of a written score I can quickly copy it in ABC and play it back. I have access to a huge online library of tunes on the internet, and compared with other file types the ABC files take up very little memory. However my hard copies of music are all in notation, not raw ABC.