Uh, useful, I guess? If you're using SMZX mode and need to display text, I'd recommend making a custom font to fit the situation, as it will really depend on context how good it needs to look and how many chars each letter should take, or even if you need every letter/both cases. These letters are passable as a temporary replacement for the default char set in SMZX mode but I wouldn't dare release a game that uses them.

10 years later edit: joke's on me I guess, the font is the main part of this character set that sucks and it's almost entirely from the default SMZX set. The graphical/UI elements are fine and I can imagine these would be useful to copy into your own game (with a different font please).