Beatwave is the best grid based music maker that Ive found on iTunes. The sounds really set this apart from the others. I really like the chip tune palette.
Even though you can tune on note labeling it would be helpful to see black and white keys like on a piano roll editor. I wasnt able to scroll beyond two octaves so I couldnt easily recreate my songs. Also I wish there were a grouping of sounds by category. I would also like more song export option besides a ring tone. The sounds on this are top notch!
Beatwave certainly kicks tail in the sound department. A few more tweaks will have other grid based apps running for cover. Definitely give this a try.
The Organist about Beatwave, v2.6