It seems that some people have some quite strong views on the "right" way to track progress. Here's my view.
In the red corner, we have the traditional burn-down graph. You start with a certain amount of estimated work, and as you finish it you cross it off the list. You finish when you hit zero.
In the blue corner, we have the burn-up graph. Here you still have a certain amount of estimated work represented as a line across the graph. Work is added cumulatively and you finish when you reach the target amount of work.
OK, so what's the difference? In my opinion, not much. Some suggest that a burn-up graph is psychologically more motivating because it is going up. Others I have spoken to prefer to see completion as zero, and like to see work left heading downwards. Personally I'm with the burn-downers.
Another factor in choosing which way the burn goes might be ease of changing the goalposts - in other words, how easy is it to add or remove from the backlog estimate. Let's throw in 50% more unexpected work into iteration 7:
Again, much the same. Personally I prefer the burn-down since to me it is more obvious that work has been injected, but again, others mileage varies.
So does it make any difference which you use? Is one "better" than the other? In my opinion, no. Having used both, as far as I can tell it makes no difference whether you burn-up or burn-down. Decide which suits you/your team and don't get bogged down in unnecessary debate about which is best. The important thing you are doing is tracking real progress, and adapting to what it is telling you.
That said, I have no doubt that debating the pros and cons of burn chart direction makes for a fascinating late night bar conversation at the conference of your choice....