First of all, I enjoyed the book and it made me want to read Ulysses again (which I'm doing now), so it certainly achieved something. Declan Kiberd is an eloquent enthusiast and advocate for Joyce. And I loved his idea that you should treat Ulysses like a favourite album, and skip the bits you don't like - a refreshingly liberating approach to a book that can drag at times.
I was disappointed, though, that the author assumes you will know Ulysses fairly well already. So, for example, he refers to the "Ithaca" chapter, or the "Eumaeus" chapter, and you're supposed to know which they are. And in his discussion of the Oxen of the Sun sequence, in which Joyce parodies a number of old styles of written English, again, you're already supposed to know which bits parody which styles (I don't - I wouldn't know a parody or an original passage by John Henry Newman if my chips came wrapped in it).
And I wish Professor Kiberd didn't regard every activity that comes to nothing as "masturbatory", or every group activity like a sing-along as a form of orgasm. But maybe that's what studying Joyce does to you?
It's a good read if, like me, you're an amateur fan and want some insights and a good reason to take the original down from the shelves. But does anyone seriously think any more that reading a novel - even Ulysses - will change the way you live..?