I think i saw a review that was titled somethng like worth it for the bonus disc alone. I agree a lot of the songs on the regular three discs stick close to the studio versions. Some are just as good and some are not Chicago toured hard back in the day and at this point in their tour were tired. As far as the fourth disc is concerned there are three songs that are better than the studio versions.1. Listen2. Sing A Mean Tune Kid3. South California PurplesI urge everyone to listen to South California Purples it gets stretched out here to an amazing 12 minutes. Listening to this will have you realize why Jimi Hendrix said that Terry Kath was better than himself. Terry plays some of his best and most intense playng on this song he absolutely shreds. Robert Lamm gives a great vocal along with lots of Hammond B3. The rest of the band is great as well, you will not be bored during the 12 minutes!!!!!