I was pleasantly surprised at how well this thing held up during our recent vacation.
We really checked our carseats (because we were REALLY late and didn't think we would have time to gate check them). We were able to fit TWO FULL SIZED CAR SEATS into one bag. I carried them on my back (my 5 yr old said I looked like Santa) using the twin handles. It was uncomfortable, but it worked.
The bag and handles held together and made it through three plane trips, including a detour through extra airports and snow when the airline lost our baggage. (I mean, really, how was that even possible with a MASSIVE red bag?)
The only complaint was that in all of the jostling, the string came out of the mouth of the bag where we had tucked it. It must have been dragged along a belt pretty violently because the string was fused in a knot - it had melted together and there was no way to untie it. Fortunately, it came with enough string that I just cut out the knot, retied it, and it held through the return trip.
Overall, I would recommend the bag as a way to keep the carseat clean, make it more identifiable, and to haul it through the airport. It doesn't offer any cushioning, but there is PLENTY of room to wrap your seats up in a blanket or two to give it a little extra protection.