If you are a frequent flyer on Frontier Airlines, then this is a card that you might just want to consider. But this is not the only card that can earn you Frontier miles so we'll now look at the pros and cons before coming to a conclusion.
To start off, you do not get your "first baggage checked in free" as a perk for this card, unlike many FF cards that offer this benefit. That may or may not be a problem for you. If you are an elite member of their loyalty program (specifically the Summit and Ascent Level), you get your first two baggage checked in free (regardless). The third bag is always a $50 charge.
You can also get your first two baggage free if you book "classic and classic plus fares". Classic fares are $100 above economy fares and Classic Plus fares are $175 above economy fares and are fully refundable. They both have different perks that economy fares do not have.
Therefore, if you are are always purchasing classic and classic plus fares or are Summit and Ascent levels, then the lack of "free baggage check in" feature should not bother you. But regardless of fare type, you still have to pay a $50 fee for your third baggage.
Another feature that this card does not have is that they do not have any free lounges passes for their card members. But that is not really an issue because Frontier has hardly any lounge at all. They do have a Best Care Lounge at their Denver Hub (former MidWest Lounge) and not much else.
One of the things that I really do like is the low annual fee. At $59, this must be one of the lowest annual fee for FF cards. The average range is about $85 to $130.
If you fly to or from Denver International Airport, the three major airlines you will be taking will be United, Frontier and SouthWest. SouthWest is gaining market share on both these airlines at this hub, but Frontier considers you ski equipment as your baggage. So if you go to Colorado for skiing often, then Frontier might be your preferred choice! If Frontier is the only airline that you fly, then this would be a great card to get and it will definitely help you to earn more miles. If you fly other airlines (not SouthWest or United) as well, you might want to supplement it with the Premier Rewards Gold Card (Details here) because you can triple points on airfares and transfer points to your Frontier account. Occasionally, Amex will have a bonus promotion where you get extra points when you transfer them to a particular airline.
If fly from Denver and fly both Frontier and either SouthWest or United (or all three), I will still be tempted to get this card simply because the annual fee is low.
Conclusion - I would end this review by stating that this is a decent frequent flyer card. It does not have features like free checked baggage, free club lounge passes. But the lack of these features is due to their other corporate policies than the card itself. If you fly this airline a lot, then we would not hesitate recommending this card.