JExcel is definetly for you if you have JIRA Core or JIRA Software licence and ...
are just getting to know JIRA
are heavy users of it but
use Excel and JIRA simultaneously
miss some Excel-specific features from JIRA like
an Excel-like view of their issues
an Excel-like way of creating and editing issues
importing and exporting their issues from/to MS Excel
copy-paste (also to/from MS Excel/Notepad)
an Excel-like way of filtering and sorting issues (without JQL knowledge)
seeing the Average/Count/Sum of the selected cells
So, JExcel is basicly for anyone who has to deal with issues in JIRA.
If you like our features, don't hesitate to use them!
And if you don't... it makes us sad, so help the Earth be a happier place and let us know why you don't like it.