I've been working with the JDeveloper 11gR1 XSL Mapper for years. And I think I became quite handy with it. I find it a great, impressing tool, since you can actually drag and drop pretty much everything together. When you draw a line, you can drop a function on it. When you think a little about the sequence of drag&drops you can tie up a pretty complex logical expression together. However, there are a few annoyances that I keep running into. I think they're bugs, or at least very unwanted behaviors. Since I keep running into them, I'll write them down, so maybe it will be picked up by the development team, or at least you as a reader can take advantage of them.

Call-templates within for-each

 The first one is a very tricky one.
If you add a for-each construct in your xsl-map, all the expressions below them should be relative to the select attribute in the for-each construct. And the XSL-mapper does a pretty good job in keeping track of these relative xpath-expressions. Except in parameters of within the call-template constructs!!!
This is very risky business, since you need to edit each occurence of a call to a user-defined template by hand. And you need to check this pretty much every time you did a change of the xsl-map within the graphical designer. Because it messes it up every time.
Here's an example of a not null-check of an element from the database adapter. You see that the xpath of the if-test should be the same as the path in the select of the with-param. Except for the not(..@xsi:nil) construct in the if-test of course.

                  <xsl:if test="not(eigmat:personen/dbfuncmat:geslachtsaanduiding/@xsi:nil)">
                    <psn:geslachtsaanduiding>
                      <xsl:call-template name="lookupGeslachtCDD">
                        <xsl:with-param name="sourceValue"
                                        select="/eigmat:rootElement/eigmat:subElement/eigmat:personen/dbfuncmat:geslachtsaanduiding"/>
                      </xsl:call-template>

Formatting when global variables or user-defined templates

The second one is annoying, but not so functional problematic. When you declare variables at the beginning of your xsl-map, before the main template, then after an edit in the graphical map-designer, the formatting is a little messy. It will put the first variable-declaration behind the opening tag of the xsl-map. Then it places the second attribute on the next line, but indents it and starts the second variable on the same line, and so on:

                exclude-result-prefixes="xsi xsl eigmat dbloc dbfuncmat xsd loc ns5 psn version ns1 mat dom jdz bas rel xp20 bpws bpel bpm ora socket mhdr oraext dvm hwf med ids xdk xref bpmn ldap"><!-- globale variabele declaraties --><xsl:variable name="targetApplCode"
                                                                                                                                                                                                                                                          select='"NUT"'/><xsl:variable name="sourceApplCode"
                                                                                                                                                                                                                                                                                        select='"APE"'/>

About the same occurs with the user defined templates after the main template:

  </xsl:template>  <xsl:template name="getCurrentTime">
    <xsl:value-of select='sdf:format(sdf:new("hh:mm:ss"),date:new())'/>
  </xsl:template> <xsl:template name="

It can be solved quite easy by giving an enter after the opening tag of the xsl-map or, for the templates, after the closing tag of the main template. Then do a reformat of the xsl-map and the formatting is neat again.