I tried to set up filters in a database import block for a text field "does not contain" a text string.
1) The query returned no records, as the SQL generated was looking for it to contain the text.
2) And while clicking between the "Configuration" "Filters" and "View SQL" tabs it has lost my field selections and gone back to select all
3) Minor UI issue, if you expand the View SQL box horizontally the text wrap extends out so that the SQL string extends across the available view. If you then make the view smaller horizontally it doesn't re-wrap the text but puts a scroll bar on the horizontal axis of box - minor problem, but what's wrong with perfection!