Whilst this is viewed by many as the third GitS film, it is - in actuality - the third installment of the highly successful Stand Alone Complex series.
SSS follows on from SAC 2nd GIG - if you haven't seen that then stop reading and watch it - and follows Section 9 two years after the events of the Individual Eleven case. After the events surrounding Kuze, the Major has left Batou and the rest of the group, and Secion 9 has - as a result - fallen into the responsible hands of Togusa, who has developed greatly in his skills and experience since Motoko's departure. The story now revolves around a new enemy to Japan: an unknown Hacker named the Pupperteer - for those of you who have seen the original film and are thinking that this is just a rip-off on the Puppet Master, you're mistaken. Section 9 is presented with a series of suicides by military refuges and must search for the Puppeteer before a civil war breaks out within Japan. However it would seem that there is another unknown presence that is watching over the work of the Puppeteer.
Whilst Solid State Society is, more or less, a third installment of the SAC series it is presented more beautifully than the two GIGs, with much improved CGI imagery and excellent voice work. Mary McGlyn returns once again to perform as the voice of Motoko, and Origa (the singer who sung the intro themes from the first two SAC GIGs) is back to sing the intro and ending themes for SSS. On the topic of the music, Yoko Kanno is once again back and creating greatly atmospheric and emotional themes that accompany the action on-screen perfectly.
Solid State Society continues to follow GitS's perfectly complex and political issues, but seems to have followed SAC 2nd GIG more than the other films or series, as it maintains a realtively dark atmosphere throughout it's duration; that said, no GitS film is really all that light-hearted.
The film itself is worth buying, as it's a great addition to the SAC universe, however there are also a couple of great extras packed onto the second disk of this set - although Amazon has only stated there's one disk there are actually two. On the bonus disk you get the interviews with the director, designer etc. just as you did with the two SAC GIGs. However you also get a nice bonus with an extended episode of Uchikomatic Days - the Tachikomatic Days from the SAC GIGs obviously cannot continue due to storyline purposes.
The overall quality of SSS is very high, with it's only real downfall being that you don't get the same kind of feel for the Puppeteer as you did for the Laughing Man, Kuze or Ghoda. However that was always to be expected due to the fact that this is a film, not a 26-episode series. All the characters that you've grown to love appear in SSS, and unlike GitS 2: Innocence you are not left with a nasty taste in your mouth once the credits begin to role.
Overall I would recommend this to anybody who enjoys anime, and expecially to those who enjoy GitS and the Stand Alone Complex universe. However, be warned that unless who have watched the previous installments of SAC, the events that occured will be revealed in the course of Solid State Society - so I recommend you watch those before you buy this.