Lots of trouble getting this plugin to work, but I kept coming back to it because it's the only one which seems to deal with custom taxonomies, and allows you to specify the post plug, both features I needed in my application. In the final analysis, it is working, and I am very pleased.
The plugin's philosophy is "follow my format". You need to label the columns the way it needs them labeled. This is slightly inconvenient: it would be nicer if you could map your column headings to theirs. This is why I downgraded to **** instead of 5.
A lot of my issues, I believe, are due to my working on a Mac. The native MAC csv files that Excel 2008 wants to generate are not compatible with what this plugin wants; the program purports to output windows-style and dos-style CSVs as well, but none seemed to work.
It was tough to figure out a process that worked. Open Office on the Mac didn't really help: files which included quotes just weren't being escaped properly. At one point I was uploading an ODS file to a MySQL table, and then exporting a CSV using phpMyAdmin. The resulting CSV file would upload via the CSV Importer properly as long as I selected the correct CSV file format variant at export-time (phpMyAdmin gives you at least 3 different ones and I frankly forget which permutation worked: but one did).
The problem is that I wanted my CLIENT to be able to do this, and I thought this was pushing things. Ultimately I realized I could run Excel 2007 under Windows and it would generate an acceptable CSV. The client is a Windows shop anyway, so should be OK.