The idea behind bottles...

1) Does not impart any metallic flavors to the brew - though most cans are plastic coated inside.
2) What I have seen is that beer just TASTES better if it was bottled instead of canned.

call me a "beer snob", but honestly trying Guinness in the can and bottle and taste testing them, without knowing which was which (we once did a double blind test at a friend's house, lol) we COULD tell there was a different flavor and it wasn't as good. It turned out after several of us chose the "good" and "bad" the "bad" was always from a can.

It MIGHT be that we got a bad/old batch, I dunno, but that was the conclusion. Haven't really drank beer in a can since.