The arguments against the Book of Abraham are very old and have been addressed countless times. It never ceases to amaze me that those who research the Book of Abaham go to the anti-mormons to get their answers instead of going to pro-LDS sites to find out what the church has to say about their questions. Here is a site that addresses most, if not all, the doubts that people have raised regarding the Book of Abraham:
Book of Abraham
Book of Abraham