in MW 1.25 I can see the orange exclamation mark, but nothing else. It is not working at all.
Topic on Extension talk:SemanticComments
Appearance
the solution for this is to replace
'dependencies' => array( 'ext.smw.sorttable' )
with
'dependencies' => array( 'ext.smw.sorttable', 'ext.jquery.migration.browser.js', )
in CE_GlobalFunctions.php on line 181. And to put the script ext.jquery.migration.browser.js from /extensions/SemanticResultFormats/resources/jquery/ to the scripts directory of SemanticComments.
Then it seems to work, but no new comments can be added (see my remark "Not working in MW 1.23.10" below).