Anyone buying this album will probably know the music inside out, as is often the case with CD-issues of popular records from the vinyl era. Therefore the question for a reviewer trying to be helpful to others must be whether this version adds anything to what has previously been available, and if the sound quality is really an improvement.
First the sound. Since I own both the original UK vinyl pressing and the 1997 re-issue of this album, it is quite easy for me to compare. These things, of course, depend on personal tastes, but I do NOT find the sound is improved with this version. Compared to the 1997 release, it is harder and more polished sounding (and strangely, the stereo image appears to have moved very slightly to the right, though you will only notice that using headphones). If your system is a bit dull, however, or you've been at too many loud rock gigs in your life, you may find that this current disc sounds "clear and crisp", or whatever terms people use about CDs these days.
This Special Edition offers as extras a number of very interesting outtakes, demos and alt. versions. Personally, I prefer some of them to the album version, which had a few too many overdubs for my taste. Some of these tracks may also appear on the Jam Box Set (which I haven't got at the moment).
Finally there is a DVD with the three members of the Jam talking about the making of the album. It seems that the producers were unable to get them in the same room together, which is a bit sad to say the least. For musicians there is very little in the way of explaining and showing the techniques that were used in the studio, so instead we're given more-or-less the pretty well-known story behind this classic album.
Finally there is a small booklet with sleeve notes.
If you want these extras, this album is worth getting, but for the sound alone I would recommend the 1997 release or the original vinyl. There is also a CD version from the 1980s around selling for chip money, but I don't know what it is like and I doubt it could be better than the one from 1997, as generally CD from the mid-90s have the most natural and "analogue" sound.