Make sure to mark your calendar a year from when you get the card. They waive the annual fee for the first year, but after that they start charging you $69 a year. I called to cancel before the year and they waived the annual fee for life. Even if they don't waive the annual fee and you cancel the card don't throw it away as it will allow you to skip check-in lines and board the plane ahead of people traveling with small Ch*ldren and those requiring extra assistance, etc.
Spirit pretty much always has the 15,000 bonus miles with the first purchase on their credit card. However, your link looks a lot like the personal url I recieved
http://www.3freeflights.com/119094290 and you left out the part that says,
"When you refer your friends and family to sign up for the FREE SPIRIT MasterCard, they will get
3 FREE flights after they make their first purchase and so will you."