A can is a superior packaging device to a bottle for two main reasons.
First, the can is impervious to light, while a glass bottle is not, and "light-strike" is an issue for beer, as it can cause "skunkiness" in the beer. Here's the science for Cincy: "Light triggers the breakdown of hop alpha acid compounds to form a dimethyl allyl radical. This reacts with thiol sulphur-containing compounds to create 3-methyl-2-butene-1-thiol (MBT) which emits pungent 'skunky' or 'cat pee' aromas." This is especially prominent in beers packaged in clear or green bottles, while brown bottles offer some protection, but not as much as a can.
The second reason, is that a can simply seals better against air, than does a bottle cap. Air exposure over time causes oxidation in the beer which degrades the lively alcohols and aromatics, rendering them dull and bland.
Regardless of the package, however, all beer should be poured into a glass and consumed that way, for maximum impact.
