I was surprised at how much I learned. I initially thought I would just be reading about a bunch of uncivilized bands of people. It turns out that our stereotypes of non-Roman groups have largely been the result of Roman propaganda.
Jones clearly did a lot of research on this book, and I was amazed at the amount of detail given. For example, I had no idea that the Celts were better at metal working than the Romans and that the Huns were from Hungary.
In short, I was highly impressed at his work and hope to read more of his work. Clearly in addition to his well documented sense of humor Jones is also a scholar of reasonable caliber.