Just read through this
http://www.ecb.europa.eu/pub/pdf/other/virtualcurrencyschemes201210en.pdf Half of this 55 page report concerns Bitcoins, ranging from legal, technical and political issues.
The conclusion is quite positive as it states that Bitcoin is not violating any EC virtual money or currency laws.
The paper also expresses the usual concerns; ponzi, money launder, non backed, terror funding, but find the risk of such transactions happening at any scale, very low.
Their main concern, which is mentioned in 3 different chapters, is that if there are more conventional banking fuck-ups, Bitcoin can gain traction fast, if supported by mass media, and be a threat to the trust in established financial institutions.
Strait talk report, high quality level of research into different aspects around Bitcoin.
Worth a read and to take along, if you have some explaining to take care of, with your local IRS office.