As with most things, there are risks. The price of shares is driven by supply and demand, and the dividend is driven by ASICMiners ability to maintain market share in the mining network.
They intend to scale up their mining operation as time goes on, and as difficulty increases, and they hope to maintain a roughly fixed percentage of total hashing power. This means that the dividends should be somewhat predictable.
I'm bullish on ASICminer because I believe in the approach they take. But, I dont care much for peoples opinions on what the "true" price should be, since all that matters is the current price, and your current opinion on whether that price is high or low.