I only have experience with carry-on, so I cannot speak to the whole cargo side of pet travel. We have a small Havanese that loves his travel carrier and has been on several flights. We brought him here under the seat in front of us on a Copa airlines flight from the US at the beginning of September and he did great. Of course, we knew our dog and that he is comfortable in his soft airline approved carrier (he prefers to sleep in and hang out in it even when not traveling) and is very chill on plane rides, so we knew this would not be particularly traumatizing for him. He did wonderfully, just rested and was ready to run and play when we arrived. I think you just have to know your pet and whether they can handle something like that, and what to provide them with to make it as comfortable as possible.
As for the paperwork, if you are coming from the US you have to have a USDA-accredited vet check your dog out within ten days of your flight and he/she needs to be up to date on rabies vaccination. Your vet needs to fill out an International Health Certificate form for Argentina, and then you have to go (without your dog) to a local USDA office to have the paperwork certified. When you check into the flight, the attendant at the desk should* ensure that you have your proper paperwork (the Intl Health Certificate and proof of rabies within 10 days signed by your vet). The Copa airlines people asked for it when we checked in before they would allows us to continue.
Once you land at EZE you have to go to the SENASA office near the exit from Customs, and handover all the paperwork. They asked us a few questions in Spanish and looked over things, had us sign a form and pay the animal entry fee, looked at our dog just to make sure he seemed healthy, and then we were on our way. It was really rather painless. They even provided paperwork with instructions on what we need to do in a few months when we leave, which is basically just the same process for coming here (replacing USDA with SENASA) and they provide a number to call if you have any questions.
As long as you have the proper up to date regulation information and all the paperwork, you should be fine! Then it's just a matter of how will your pet do on a flight.
If anyone travelling from the US with a small carry-on size pet needs more help, PM me.