Upon a time I have had compared the results of various notations side by side in my own blog, split into several posts. But comparing them within one single post is cooler, and easier for comparison purpose. So here presents the beginning 2 bars of Prokofiev Piano Sonata No. 8, second movement:
ABC:
Guido:
(no midi download)
Mup
(no midi download)
Lilypond
(no midi download)
PMW:
Among all notations, Lilypond takes me the most time to get positions of various dynamics and texts right. Much time is spent on Guido one too, but documentation on Guido is considerably easier to read than Lilypond’s, and much manual layout simply can’t be done by Guido 
.
I have been saying that ABC notation shows promise; now I want to take back to word. It doesn’t even allow specifying text marks in arbitrary position! This is 2008, not 1988, but still. Though ABC standard version 2.0 has it, but (1) it’s a draft, and (2) which software is implementing 2.0 standard?
The above paragraph partially reflects my lack of understanding of ABC format and abcm2ps, which already tries to implement 2.0 draft standard.
2008-09-28 Edit: Add Philip’s Music Writer counterpart since it is recently supported.
2010-02-21 Edit: Recently upgraded PMW to version 4.21, now adjusting staff spacing is not allowed for staff 0 (Tempo). Besides, ABC fragment is adjusted a bit, so slurs and expressive marks are correctly placed above/below notes. One problem remains: position of dynamics still can’t be adjusted.
