Couldn't he have been both? Caesar was a sound general, having some ability in both strategic and tactical details, while lacking strength in others. For instance, he was more than capable of forward strategic planning (such as the invasions of Britannia, regardless of the outcome) and showed brilliance in siege warfare. Conversely, he was reactionary and brash, failed miserably in most logistical affairs and was often quite close to defeat before ultimately scratching and clawing a way to victory.
As such, it's just as easy to say that he was both a great military mind and a brute (and a tyrant for good measure).