Let's stipulate that Research in Motion president and co-CEO Mike Lazaridis doesn't have the flair for delivering the dramatic product launch that Apple CEO Steve Jobs has become known for. Who does? But that places more weight on the new product to sell itself. In the case of BlackBerry-maker RIM's PlayBook tablet computer, unveiled Monday, the device itself didn't close the deal. Despite its sleek appearance, "less than one pound' weight, Wi-Fi connectivity, and other features, a number of key questions remain about the PlayBook.