I use ASD, either the desktop or the iPhone version, daily to learn traditional tunes. I've tried the others that previous reviewers have suggested and I always come back to ASD. Ironically, the reasons I always come back are the same reasons that some don't like the program: The interface is not especially Mac-like, but it is perfect for ASD. Pretty much everything you need is displayed in an uncluttered, logical fashion in a single window. I find ASD very intuitive and easy to use. There aren't a lot of features like tablature, multiple markers and so on, but for someone who wants to learn tunes by ear it is perfect.

Different users have different needs, and ASD probably is not the best choice for some. It is, however, the best for me. The only way to know is to download it and try it out.