That sounds like way too much. It's more likely it makes use of DC power at 5V or 12V: the fact it has an integrated adapter from AC to DC only means it's harder to figure this out.
A first AC/DC adapter I grabbed has an input of 0.1A at 230V and output of 0.5A at 10V. If your device has got a similar ratio (there is nothing to say it does, though :)), you are looking at 3A at 5V or 15W max.
Agree, listing only 0.1 A without saying at what voltage is is not informative. Recently bought a power meter and it says it actually only consumes 2.4W. I posted my correction on the replies above
A first AC/DC adapter I grabbed has an input of 0.1A at 230V and output of 0.5A at 10V. If your device has got a similar ratio (there is nothing to say it does, though :)), you are looking at 3A at 5V or 15W max.