Hi Fran. I've read Alien Interview and I couldn't put it down at the time. I enjoyed the character Matilda McElroy and the story had a positive feel to it. If you have a general understanding about what supposedly happened at Roswell its not hard to believe that this narrative could have occurred. That said after some research, I found that there are some who've looked into the author Lawrence Spencer and suggest that its a fictional story written from a Scientology perspective.
see -
http://wespenreproductions.boards.net/thread/421/lawrence-spencer-book-alien-interviewor -
http://projectcamelot.org/Alien_Interview_review.pdfIf the books message appeals then it's authenticity may not be as important. Hope this helps.