One trick pony does what it does. If you need drill and practice for intervals it seems simple enough to set up and use. (I'm a tech person not a musician) My comment is just to note that it is not "Free" nor "Shareware". It is a 30-day Demo then $9.95. V. 1.x for PPC-only was freeware I believe. Seems like a reasonable price for v. 2.x and it runs on OS X 10.9.x