I know a couple of guys who have retired here from the US. They did it about 8-9 years ago and are a bit unhappy due to the inflation in the last few years and what their retirement benefits buy now compared to what it bought when they moved here. Fortunately, the own their apartments which helps significantly for them.
Things are a bit uncertain here at the moment (feels like a lot of people are waiting for a cliff to come up - the working class Argentines and foreigners are struggling mightily, middle class maybe not so much but still not real happy) and no one really knows exactly what's in store for the economy, but good things are less likely than bad. However, at some point things will probably calm down again. When things are stable and if you're happy with prices how they are now (come a stabilizing here, I doubt it will stabilize more expensive than it is now, although there may be worse inflation in the shorter term) then you would probably be alright pension-wise.
As far as getting your personal things in the country, yes, as a legal resident you have a window during which you are supposed to be able to bring in your personal belongings duty-free. The reality, however, may not be so simple, given the import restrictions that have been imposed. I'm sure everyone here probably remembers the recent Olympic games and how the Argentina teams themselves couldn't get their sports gear in to start practicing. It's been a while since that, of course and some things may have gotten better.
I know a US couple who moved down here a few years ago, before the import restrictions were in place. They moved their belongings down here via container and the container sat for a week in customs. They were charged $5000 USD in duty, even though the law says otherwise. They were welcome to fight it, but the storage fee was $200 USD per day. They came to a settlement with the customs agents (i.e., paid coima/bribe, through their shipping agent they were using down here) to pay $2500 USD, but they also had to pay the storage fees.
Importation and the economy - two of the most uncertain things about Argentina.