That's interesting, I may look into it. However, I find it to be a very risky investment, because the price of bitcoins fluctuates so much. Still, its somethign that I will consider doing.
I find it a safer investment than bitcoin itself:
The Bitcoin fluctuations are irrelevant to them or you: you receive dividends in Btc.
The company has a (recent) positive track record - pays big dividends, profits, is transparent.
Their machines are custom machines of theirs - not some Avalon rigs purchased by a few friends - and they are upgrading as they go to keep up with difficulty.
The one negative is that the shares are not traded openly (you buy a "pass-through" which is the eq of a share) - you have to go on btc.tc to buy the share. It's still relatively easy to aquire some, but there isn't too much volume: a lot of people buy to get the divs, not to resell.