I love this plugin, and have it running on 3 different sites. But I've noticed a flaw in the install files:
In the core plugin file simple-import-users/simple-import-users.php, there are two hard-coded instances of a blog name called "Blogs@Baruch". These occur in the subject of emails sent to new users and in the text of the email itself.
So upon install and activation, it is necessary to edit the plugin files to reflect your actual blog/site name. Otherwise all your new users are sent emails with subject lines reading 'Your Blogs@Baruch account has been created', and body text also referencing Blogs@Baruch.
Hoping one of the plugin developers sees this and makes the change to a future version!