lol's
very clear hill sprints are not overated by the comments
As a track sprinter and coach, we incorporate hills all year round in some form or another.
Most people who dismiss hill sprints are those that are too lazy to actually give them a proper shot as they probably suck at it and so don't want to give it the time away from the precious asphalt.
As stated though downhill sprints are an absolute must and I mean...MUST! for track sprints.
You can find details on hills for sprinters by looking up for asafa P training session on youtube