Hegarty's major advantage is organization. There is a very clear development throughout the book so that each chapter builds on the last. I can understand the difficulty in figuring out a way to present Bataille's philosophy in a linear fashion and Hegarty has succeeded where others have failed. Naturally, one can only do so much to take complicated philosophical concepts and reduce them to a 180-page monograph, so the reading isn't exactly easy. Hegarty addresses this by carefully providing one or two examples to illustrate major points. If you don't pick up on it initially, you have a second chance to understand. Hegarty also doesn't require the reader to possess a great deal of background knowledge. Hegel and company make a few appearances here, but these ideas are carefully explained.
That said, I have a few complaints. Hegary has read Bataille in French, which means that all of his citations are for the "Oeuvres Completes" of Bataille - his collected works in the original French. This is great from a scholarly perspective because his understanding of Bataille is not filtered through translators. However, it's a pain for regular readers who might want to look up some of these concepts in Bataille's English translations. Hegarty introduces the concept of, say, heterology and I want to read what Bataille actually wrote about that concept, but Hegarty sends me to the collected works of Batialle which is a) in French, and b) a hugely expensive reference collection held by only a few libraries. Really, I want him to point me towards the books that I actually have on my shelf.
My other complaint is that Hegarty himself steps in to defend Bataille against future critiques of his work and if one is not a critical reader, one may not realize when the author shifts from an attempted "objective" explanation to an opinion that is not neutral at all. Derrida had some interesting opinions on Bataille, but Hegarty dismisses them a bit too easily, in my opinion. However, Hegarty does offer his own criticisms of Bataille, so it's not like this is hagiographical or anything.
Overall, this is an excellent introduction and it's a shame that it's only available from a small academic publisher from the UK because it the price automatically puts it out of my reach. There are other introductions, but they do not offer the same conceptual clarity that I find in Hegarty. I actually own the Kendall and Noys volumes, but when I want to look up a concept like, say, the 'general economy,' they do not offer good tables of contents, nor sufficient indexes. I always thumb through them and end up frustrated that finding information within is not easier. They are, however, much more inexpensive.
My advice is to skip the cheaper introductions. Go to your library and pick up Hegarty's book, or splurge and pay fifty dollars for this tiny paperback.