In order to be conscious enough to sit through 3 hour lectures and 2 hour practical classes, sometimes a caffeine hit is needed.
I normally buy a regular sized cappuccino. This costs $3.20, which is decent value when you compare it with the cost of a Gloria Jeans coffee or a coffee from a cafe in the Mac Centre (which is closer to $4).
My experiences with the coffee available around MQ has been very hit and miss, in terms of quality. Sometimes the coffee is too weak, while other times the coffee's milk is burnt. Its all just a matter of luck, unfortunately.
If coffee isn't your thing, the coffee carts (which are conveniently scattered around campus) are still worth a look as you can buy hot chocolates, cold drinks and muffins.
For those of you considering buying coffee from an outlet around campus, although its not great, I would still recommend it based on its value for money and convenience.