I'm a new user, I don't know much about spreadsheets.  I'm getting more errors
than valid cells.  What I'd like to see is the full text of the error instead of
an error code.

As I started filing this feature request, I noticed the bottom right corner of
the screen shows a one-line error message when I'm on top of the cell with the
error.  This is better, but it was hard to find (the first time anyway) and it's
only one line.

What I'd recommend is a tooltip for each cell with an error, giving a paragraph
on what the problem is.  Alternatively, if you right click, you can open a help
window about that error message or the function that caused the error (if it's
not a misspelled function name, good luck finding a help page for that).

Note: this is an enhancement request; go fix real problems first before doing this.