Three stars, not five.
Functionality is adequate: set as many reminders as you want and configure the time. Coupon integration is very useful.
However, there are some definite shortcomings:
(1) No documentation. You have to dig through source code for a list of allowed "tokens"
(2) There is NO ability to create custom html for the email via the admin interface - the TinyMCE editor may be fine for basic html, but entirely drops the ball when it comes to the highly complex needs of html formatting that is required to get a good looking email. You will want to manually stuff your html code into the database.
(3) CRITICAL! No means to insert unsubscribe link to allow customer to opt out. Thou shall not send email without an opt-out!