So, now that I've read the bulk of the F+GM stories? They're still tentpoles of the canon, as far as I'm concerned. The prose very deftly slides between action, humor, and lyrical tone-setting. (The image of the world of Nehwon as an airy bubble rising through an infinite sea will stay with me; and, again, it must have been an inspiration for Pratchett's ironically clunky worldbuilding.) Nehwon is a very tangible place, Lankhmar more so, and the repeated intersections with our world, if patchwork, are confidently so.
As for the Fairies of Infelicity -- I think they've pooped less upon these stories than you might expect of the era. Nehwon is a big place of many nations and ethnicities; we see national stereotypes (the Mingols as outskirt nomads) but not unmixed ones (our heroes spend several stories sailing with a Sea-Mingol boatman). The women in the earliest-set stories wind up dramatically dead, but for most of the series the female characters show up as plot instigators rather than plot tokens, and pull our heroes into bed or not as appropriate to their schemes and desires. (With the blatant exception noted above.)
So, overall: worth keeping in one's library.