I have the black and pink pet flys carrier, and I am happy with it. Mia is on the bigger side, so I got the small size, which accomodates pets up to 12 lbs. I must tell you though, it is not fun to carry it around for long periods of time. My shoulders start hurting after 20 mins. But, that could also be because missy Mia is 5 lbs. already.
Many people do not notice that there is a pup in the bag right away, but it looks like a duffel bag. After learning that Mia was inside, someone told me that she had been wondering why I was walking around with a duffel bag. Also, I have to carry around my purse when I take Mia in her pet flys, because it has no compartment for a wallet and a cell phone.
However, Mia loves sleeping in it. After she got used to the bag, I can plainly see that it's like her second den. She feels comfy and safe in it. I also like that it comes with a blanket, and you can wash the bottom and the blanket as much as you like.
Good luck with making a decision
This is the one I have :
http://petflys.com/pawprincess.html