Do you know how to whois a web site? If not you should not do ANY business on the internet. 84% of web sites are scams now. You might be investing in a real item (Bitcoin), bit the person handling your investment may be fake. He or she will just take your money, and invest it in his own retirement account.
I think it's a matter of trust. Do you trust that a Bitcoin - an invisible, alternative currency has a value, greater-than or equal to the US dollar/ British pound / European Euro? In the past year the Bitcoin has seen a value of $1200 - and is currently floating around $500 per individual bitcoin.
The value is incredibly volatile, and it seems to have an attributed value mostly because people no longer trust their national (fiat) currencies issued by bankers and backed by the guarantees of governments.
The value of Bitcoin lies in its intangible asset structure - it can be said to exist as an asset - but it is untraceable. This untraceability has a value to the criminal, and might be a problem to national and international police organisations trying to trace a traditional paper-trail which might be formed between illegal operators. There is also the problem that the currency is backed not by a government, but by the unbreakability of a cryptographic currency.
As has been shown with Mt Gox, the currency may be safe, but the storage mechanism where an intangible asset is located can be hacked and ownership of assets re-attributed - ie: a new form of bank robbery, where criminals can steal many millions online, is perhaps ironic.
I would hazard that bitcoins are no more real than the paper tokens we call money.
EDIT:
This may or may not be of use to you as an informational resource
Bitcoin is highly speculative and unstable at this stage. It is much more like gambling than investing.
