I'll be concise here. The original Ghost in the Shell manga is a true gem in the world of manga, philosophy and cyberpunk. 1.5 is a set of stories that didn't make it to either the original or 2, and were released after 2. This one doesn't have the same amount of speculative content as the original, and its short, independent cases are less memorable. The charismatic Major is almost entirely absent. Togusa, Batou and Aramaki get the spotlight. The absence of an overarching plotline is one of the biggest weaknesses here. Further, there is only one major philosophical theory that Masamune appears to be presenting throughout thevolume.
I also take issue with the art. It is definitely sub-par. Rougher and more sketchy than the original manga, proportions and angles are often laughably odd.

All in all, this manga is rather unremarkable, neither good nor bad. If you're going to read GitS 2, you should read this. It would be wiser to just stop after reading the original.