The default behavior in formula editor (on both Linux and Windows) has too much
horizontal spacing between symbols. That doesn't look right, and it differs from
how both Word and LaTeX (and probably every other formula editor) work. 

A partial workaround is to set Spacing = 0% in Format->Spacing..., but that
results in zero spacing between a variable and an operator, such as "a + b".
This can be corrected by entering the formula as "a ``+`` b", but that's a huge
pain to do for every equation, and it took me a long time to discover the trick.

My suggestion is to set Spacing = 0% by default, but add extra space around
operators like +,-,=, etc. That will solve most of the problems. 

The kerning rules could also be improved. For example, when I type "xy" without
a space, the two characters are much closer together than if I type "x y" with a
space between them, even though in the latter case the program still tries to
put the as close together as possible (assuming that "Spacing" is set to zero).
That proves that in the case of typing "xy" some sort of kerning rules are
getting invoked. Those same rules need to be applied for any pair of symbols
that are next to each other. 

<rant> This sort of an obvious flaw is enough to drive away many would-be
adopters coming from the scientific community. It needs to be fixed NOW!!! </rant>