Beware of the Amazon description as this is not an introduction to intertextuality at all: it's a highly sophisticated and difficult discussion of the term, its literature, and its future that assumes that the reader is pretty much au fait with Kristeva, Bloom, Bakhtin, Barthes and others. If you're not, I suspect you'll find yourself soon lost in Orr's dense prose and complicated arguments.
This is a meta-critical argument in lots of ways as Orr explores the extent to which 'our' understanding of the term intertextuality has been ideologically circumbscribed partly through the range of theorists whose work has not been translated into English, the literary lingua franca.
She goes on to explore the relationships between intertextuality and cognate terms such as influence, imitation, allusion etc. though, oddly, not reception, and has some interesting things to say about hypertext and other neologisms driven by digital media and the internet.
So this is an interesting read but a very dense, scholarly one. I would hesitate to recommend this to undergraduates unless critical theory is absolutely your 'thing' and even postgrads may well struggle.