As you saw from the picture a couple of posts down, I got my Electric Light Orchestra Out of the Blue 30th Anniversary Edition CD in the mail the other day. It's digitally remastered and sounds much better than the original first-generation CD I have. It also has three additional "bonus tracks." The first is just an alternate bridge chorus for the last song on the original album, "Wild West Hero." It only runs 26 seconds, and really is only for the completist. It might have been more interesting if it had been an alternate version of the entire song. The second bonus track is "The Quick and the Daft," a rather frenetic instrumental piece that runs 1:49 in length. It's interesting, but not really a complete song, either. The final bonus track is "Latitude 88 North," and it is a complete song, 3:24 long. It's not bad, it's clearly ELO, but it's not necessarily something that fits into the album's concept.
In a case like this, the original seventeen tracks are the original canon; the three bonus tracks are more of an apocrypha. It's strictly in the mind of the listener as to whether they add to the listening experience. I've heard the original double-album (and its format successors) many, many times over the past three decades. There's a flow to it, and the bonus tracks, especially the first two, don't really fit into it. I can always de-select those tracks from iTunes and they won't be on the iPod, if I don't want them to be.
Bottom line: Whether you want the bonus tracks or not, this version of the CD is clearly superior to anything else that has been out there. If you want Out of the Blue, this is the definitive, must-have version. And it's very inexpensive, so it's well worth purchasing for any ELO fan.
