Frontier has announced service on some of my frequent routes. I have not flown Frontier, especially the New Frontier. Can anyone offer a comparison to Southwest?

I also thought I noticed that Frontier does not include taxes and fees in their advertized fares. But after checking the charge for a seat selection, they add fees and taxes. So 2 one way $59 fares plus 2 $4 seat fees becomes $126.00 adding airport passenger charges, 9/11 security fee and taxes.

Lowest Southwest fare is $218