For me, Caesar was neither a hero, nor villain (yep, that's sitting on the fence!). I think that he was a great man, in the sense of possessing intelligence, charm, strategic ability, and sense of authority, and that in any political system, great men will rise to the top. But such men are a function of their times, not specifically of some innate character trait. The latter argument is perhaps the one that Shakespeare paints, and is one that tends to be formulated from commentators living in a society where an hereditary monarchy holds political sway - the need is there to generate history as the work of great men, rather than results of many complex social, economic and political forces. Caesar used all his abilities to the full to rise to the top, but he did nothing that previous significant Romans had also done - the seeds of the destruction of the Republic for me, lie not in any one man's hands, but in the system itself. Systems have a momentum once they start moving, and rather than men seek to adapt those systems, they tend to bend their will to make the most of the situation. Caesar gambled many times, and did so with the knowledge that the system would strengthen his position. Ultimately, the dynamics of the triumvirate (both before and after it's official formation) would become a mutually reinforcing cycle. Roman society and economy in the Late Republic was militarily expansionist, the political system reflected and supported this process. To achieve political success, military success was a necessity. Did Caesar simply play the game, and play it very well, or was he uniquely evil in his approach to conquering subject nations? That is the heart of the question. I don't see it is possible to suggest that Caesar is uniquely evil, and to that end, I don't think therefore that a picture of him as a villain makes much sense. However it is also the case that there is little in the way of heroic qualities that can be attributed to Caesar either. He was essentially just another politician on the grubby path to power, that naturally meant men who succeeded did so in a manner which was perceived as glorious (for Rome), but in all conquering hero's stories, there are always many casualties. Caesar is complex because he is such a rounded character - the polymath referred to - and that makes him very interesting, indeed his story stands out above all others from any era of Roman history - he's a great story to tell. But he is not a hero.
Cheers
Richard