Age of Worms
I ran this series first, with my Friday night group, all the way through. My basic impressions were that it started with a lot of potential in Diamond Lake, abandoned that potential, ran into some plotting issues, and then began to get back together when the group travelled to Greyhawk.
The Hall of Harsh Reflections allowed me the most opportunity to customise the adventure, as it involved a lot of wandering around The Free City (of Greyhawk), a place I've run adventures before. So, that was fun. Champion's Belt works as a logical successor to this, and A Gathering of Winds manages to provide a very solid adventure and tie-up to the Diamond Lake threads.
That these three adventures hit the "sweet spot" of D&D - levels 7-12 - and were also my favourite adventures to run probably means something.
The Spire of Long Shadows hits a wall very quickly: a lot of really tough monsters. To survive it, you really need to follow the 9:05 plan - battle, rest, battle, rest, battle, rest. It'd probably be the most improved by a 4e sensibility. Of course, it's also trying to pack too much XP into too little adventure. The "vision then XP" thing is ridiculous when used to the extent it is.
Things got back on track with The Prince of Redhand, which manages to ignore the problems encountered with high-level 3e play by being a strong-roleplaying experience. The Library of Last Resort is a mixed bag, with the first wilderness adventure not paying enough attention to the fact that the PCs can fly, as well as some too-complex encounters. OTOH, it's got some great moments.
The final trilogy of adventures deteriorate in quality; I felt confused running Kings of the Rift as I didn't think it gave the PCs enough guidance on where to go (my players not being in the habit of casting "commune with plot"); Into the Wormcrawl Fissure had things looking up, but Dawn of a New Age wandering into the realms of "we hate the rogue" too much, despite some strong set-piece encounters.
Cheers!