I've waisted my money and time on various csv importer plugins.
Last week I purchased the csv2post Plugin and I am very impressed.
The Features are just endless. From SEO to Database importing options, creating import Templates and and and.
I personally treasure that this company offers the same plugin (with less Features) absolutely free. That gave me the opputunity to test the main features.
What really impressed me, was after I bought the plugin. At the beginning I had some questions about adjusting the features. The support is outstanding and reliable. After I contacted the support, I got an answer within 1 hour. I assume with all those features that the plugin has, they must hav many programmers involved, which therefore can assist there customers.