The bonus disc is as good if not better than the original album. You may especially like the bonus unplugged tracks. And like all the Rhino reissues (now out of print), Elvis Costello provides a really fun and insightful essay.
I knew that Elvis did a lot of reissues of his albums with extra material. This is a 1991 album with extras added in 2002. The extras were definitely worth it. Some were demos, but the quality was solid.