Jared Diamond is generally disliked in these parts (while he might get too much praise elsewhere, the condemnation here might be misplaced as well). I think that, while it helps to have a healthy skepticism, his work is important in considering the big picture. It's worth keeping in mind that he doesn't really address the small picture except in isolated incidents. Eurasia, for example, is one group for the most part and agriculture (among a few other things) explains why Eurasia became dominant.
I think there's a compelling argument that what we think of as Civilization is tied significantly to Agriculture (and, to a lesser extent, domesticated animals) and our head start is crucial there. This has brought good as well as bad (Jared Diamond also wrote an article calling Agriculture our biggest mistake), but it brought about advantages to Eurasians that dominated over those who developed agriculture later or not at all.
Don't get me wrong, once you start going into the small picture, things change entirely. The environment still has a factor, but so do many other things. But I don't read Germs, Guns, and Steel as the answer to life, the universe, and everything, just as part of a scholarly contribution written to mass audiences that is beneficial overall.