Robert says they will ship by August 31. Sony says they will ship last week of August (last I checked).
Even if Sony ends up shipping a week before Astak, they still don't hold a candle to what Astak is offered up, if you compare them side by side.
This is, after all, my own personal opinion and is subject to copyright 
However, to one who has already invested heavily in Sony format BBeB books, LRF/LRX, then frankly... I dunno. I used to think they had a good, solid point. But now...?
Sony plans on switching over their entire bookstore to ePub by then end of the year, which is only 4 months away. In 4 months, Sony's books will be readable on the Pocket Pro, and any other ePub device.
After that, the phrase "I have all these BBeB books" will be moot, and the 300 will be even further outclassed. I do like the direction Sony has taken, but their ePub conversion, combined with the extreme limitations/expandability of the 300 make for a very poor business decision, and is very likely gonna end up hurting the company.
Unless there is something that I have overlooked, and am just not seeing clearly...