Lots of people get their PhD for political science from Carleton; including some moderately renowned Canadian scholars. Its more of a "big fish in small pond" thing, i think: Carleton is a heavy hitter and her Political Science PhDs are respected and can find academic work within Canada...but beyond our modest Dominion, particularly the United States, i would be alot more hesitant. I have heard several horror stories of good post-doctoral grads from top Canadian schools such as Queens or U of A being put on the same level by American faculty hiring committees as the graduates of the worst American programs simply because they weren't from either U of T, UBC, or McGill.
I personally know some of the Political Science PhDs here, and in terms of program satisfaction they cover a wide spectrum, but few if any seriously entertain the idea of getting a decent job outside of Canada, especially the US, after they graduate.
As for the Normal Patterson school of International Affairs, its not what it used to be. DFAIT has had a hiring freeze for years, yet the department keeps upping the cohort size every year, denying funding to most (masters level at least) students, et je pense que si vous ne parlez pas le francais aussi, Ottawa n'offre pas beaucoup d'avantages