Hi David,
from what I assume is your target group, here are some potential 'unclarities' (straight from the website, not downloaded):
"random note" doesn't yield anything other than blank for me. Not sure it is a needed feature to begin with, by the way.
There are small minus signs to the right and left of the " + = - " part.
The right show index arrow would be better placed more floating right.
I almost completely missed the tabs in the front tiddler! I.e the grayed out text, "Using NoteStorm" etc. This may actually be because I'm an experienced TW user though, i.e I probably subconscoiusly assumed this was a toolbar and therefore did not actively look at it.
Under "Using NoteStorm" is says how to create new indexes... maybe this is seen in the downloaded verision, but not in the online one.
I also have some purely aesthetical opinions:
Tiddler text is unnecessarily right indented from the title.
Would like the left index title (NoteStorm) to be a bit more indented (but not the index content)
I'd prefer the top bar items more spaced out.
Tiddler toolbar is also in a funny place, I'd prefer it more to the right but also lower down. (Because you use much space between title and text, maybe you could have the toolbar under the text?)
Hope this is of any value. All best.