Paizo had a lot riding on this product suceeding, launching the flagship to carry a "obsolete" edition forward. They passed most peoples wildest expectations. Spires of Xin-Shalast challenges even hardened veterans, but makes the pain and torture fun. Check my full review Spires of Xin-Shalast

Pro :
- Xin-Shalast is fully detailed (1/3 of the book) : I had the strong impression to read a city book guide (something between a whole book like the Guide of Korvosa and a single entry from Cities of Golarion) + an high level sandboxing scenario in the same time. It pleasantly surprised me.
- The wendigo/haunted cabin part is awesome
- No monster bashing unlike some other high level AP issues

Con :
- Not a real drawback but the side articles are really small (3 pages each without the title pages) because of the Xin-Shalast big description.

Rise of the Runelords terminou com um final digno e épico. A aventura final é um tratado de como conduzir aventuras de nível elevado em D&D. A campanha como um todo teve seus altos e baixos, mas de certa forma merece sua enorme popularidade entre os fãs (não é minha preferida, mas está no meu top 5), que gerou uma enorme lista de discussão que até hoje trocam mensagens discutindo atualizações para outros sistemas, erratas e formas de se conduzir cada minima parte dela. Spires of Xin-Shalast é o resultado de todo esse trabalho e mesmo assim ainda funciona muito bem individualmente. Um clássico que eu tenho muito orgulho de ter em minha biblioteca e que certamente figurará entre as melhores aventuras de todos os tempos.

Disclaimers: Review may contain spoilers
My Experience with it:
DM for one 3.5 Group and one PFRPG Group (as is, no conversion)
Overview (no spoilers):
haunts+ sandbox + hack + final fight, kind of OK
Changes (with Spoilers):
I skipped all of the City of Xin-Shalast, Sandbox-City at such a high level is nothing I want to touch, I shortened the adventure significantly by keeping out the city and the Leng stuff
Details:
The Vekker cabin was really good and creepy, the wendigo was a great monster and the haunts work OK (they did work much better with low-levels in part 2)
I had to shorten everything because most of my players don't like high level play, we take very long for every fight and campaign exhaustion had kicked in, everyone knew that it was the last part and all of them where planing new PC's and where exited to play them as soon as possible.
The giant meat-grinder was quite fun and not as exhausting as I had feared, the two ladies put up quit a fight but the apprentice was unremarkable.
The final confrontation was kind of epic and challenging even with hours of planning and preparing of the PC's - a good and proper end for a great campaign
overall:
it was the only campaign (beside a lvl16 test with converted 2.ed PC's right at the beginning) in 3edition that we kept going longer than level 10 or 11 and I think that is saying something about the quality. RotRL gave me the fun in DMing back

This adventure has everything I like, dungeon crawling, cave lurking, city walking, arena fighting, mountaing climbing, dragon slaying, fey-sighting and more! The only thing it lacks its heavy roleplaying or social interaction with other characters (at least live-non-monster characters), but at this point that way past due.

Also after you finish the adventure you have a whole city to continue exploring! There's also plenty of material you can expand to beef up your PCs up to higher levels if you want Karzoug to be even nastier.

A great 5 start sweetness!