I would approach Argentina with "cautious optimism" at best in terms of international investment with the new government.

Argentina has a very long history of poor governance and corrupt politicians.  The political landscape in that country could turn on a dime and what was once a promising investment and development opportunity in that country could quickly be nationalized and turn into a nightmare should a new government take over in the future.  The Spanish ran into this a few years back after the previous Argentina government nationalized their oil company.