Chavez' reputation as a dictator comes from his antipathy towards the US and the media's representation of him there. It's a sad fact that any administration that openly opposes the US will be destroyed
...ahem, I mean gets branded as a dictatorship (just kidding about the 'destroyed' bit, of course).
The truth is that the situation in Venezuela is fucked up in many more ways than just Hugo Chavez. It was fucked up well before Chavez came along. And while he did a lot to help the economic situation within Venezuela itself, he also directed far too much hatred towards the US than would otherwise diplomatically be advisable. He was also massively arrogant to the point of megalomania, but then the same could be said of people like Newt Gingrich. Chavez allying himself with Cuba, Iran and Syria was more to do with his ideological hatred of America than it was about common interests.
I think history will respect him for his domestic social policies, look upon him as a textbook example of how NOT to do foreign policy, and opinion will always remain divided on his broader economic policies. If anything, he did a lot to unite South America and reduce poverty in the country - that much has been proven.