The BBC makes a lot of good historical documentaries and the story of Hannibal has everything needed for a great one. This treatment was very far from it, simply because it was too short. Given the length of Hannibal's campaign, much longer than Alexander's, a two hour documentary would be the minimum.
Okay, BBC doesn't have the budget and our knowledge of Hannibal is incomplete, not to mention that much of what we do know is in contention. Still, Hannibal's genius didn't just lie in his crossing of the alps and Cannae, but in general logistics. His being able to outmaneuver his opponents again and again. I would love to have seen the crossing of the Rhone, both Trebbia and Trasimene, and a lot more detail on Cannae and Zama, all of which are timeless classics in classical history. The fact that our knowledge is incomplete also allows for a lot of opportunists for informed guesswork and gap-filling, which the producers have missed out on.
All this is a huge shame because Siddig was a very believable Hannibal and a good actor. In general, BBC documentaries do history much better than Hollywood, because attention is given to accuracy, and the target audience is more specific. It's just unfortunate that they're limited by such things and budget and time constraints. Given the length of this show, it is unlikely that it will be released on DVD, and it will be a long time before there will be another attempt at Hannibal...