Everything in moderation is what they say.

Advantages:
Caffeine has been scientifically proven to temporarily increase alertness, comprehension, memory, reflexes, and even the rate of learning. It also helps increase clarity of thought.

Disadvantages:
Too much caffeine can cause hand tremors, loss of coordination or appetite, insomnia, and in extreme cases, trembling, nausea, heart palpitations, and diarrhea.

Japan is truly home of the vending machine. They having the wackiest vending machines without doubt. Here in the UK, vending machines are very boring with coffee machines being the most popular:
http://www.klix.com/klix/en-gb