Bogotá–Medellín by bus

On the map, the distance between the two biggest cities of Colombia doesn't seem that long at first (245 km as the crow flies).

^{Bing Maps}

Then again driving distance is around 418–539 km according to quick search. Anyway, I was wondering how good an option an intercity bus might be.

With safety, quickness and price being priorities (in that order):

• General experiences on this particular route? Does it make sense to take the bus (instead of flying)?
• Are there any bus companies to be preferred (or avoided)? (Are there similar high-quality operators as in many other South American countries?)
• What's the price and duration approximately, and how often there are connections?
• Is there a website that's good for schedules?

My guidebook (Moon) seems to generally recommend flying to get around Colombia, and doesn't give those details. It does mention that Terminal del Norte in Medellín and (apparently) Terminal de Transportes in Bogotá are the relevant stations.