I'm going to start a JSP fan club, for consistently putting out excellent compilations at reasonable prices. I also recommend their Armstrong and Jelly Roll Morton sets.
My first real introduction to Django was vol. 1 from JSP, which at 5 CDs was an overwhelming but wonderful experience. Vol 2 is slightly shorter ("only" 4 CDs) but covers more ground, both in time span and variety of music. The war-time recordings that take up the middle portion of the set use all sorts of additional instruments (harmonica!), and some show a much stronger European classical music influence. Quite a few of these tracks have a suprisingly moody, atmospheric feel. Others sound more like American swing bands (Rostaing on clarinet invites Benny Goodman comparisons).
However, it is still the tracks with small string-based bands, especially with Grapelli's violin, that really throw off sparks. The first disc, in particular, is simply unbelievable, and it took me some time to move on to the subsequent discs - I just kept playing disc 1! This is the Quintet at its peak, exceeding my wildest expectations.
So, as interesting and enjoyable as the war-time tracks are, they tend to dilute the intensity and quality of the package, at least a little. I'd therefore recommend vol. 1 as more essential, and the place to start.
Packaging notes: True to JSP budget-priced form (quality sound being more important than pretty pictures), the packaging is skimpy, with all essential documentation (personnel, dates, etc.) and some limited commentary, and that's it. While the design is more professional looking than the rather amateurish graphics of volume 1, I miss Ted Kendall's chatty, personable liner notes.