I downloaded all the PDFs to date and will give them a look over.
There are three main things I can offer as advice, or learnings from running PiH.
1) Character Generation
One of my tactical errors as a DM of PiH was allowing the players to create a PC using ANY of the published 3.5E material. That led to some overly-powered characters. I think PF eliminates most of that issue, but word of warning to DMs... be careful what you allow to make sure the player characters and the NPCs/monsters they will encounter are well-balanced.
2) Planar Rules
The 3E planar rules didn't carry over the aspect of magic weakening (spell memory and item magic) on the plane as set forth in the 2E module. Traveling to the Abyss and Nine Hells was of no consquence to the abilities of the characters or their equipment under 3.5 rules. I have not seen any PF material on the planes yet, will be interesting to see how that is handled here.
3) Beyond the Module
There is SO MUCH that can be done to extend the module into an overall campaign. You can do this through the character background. For example, one of the players in my game was seeking a magical item that was reputed to be in Kroth's hoard. The group fought Kroth, but the linnorm fled, so a follow-up would be to create a maze of caverns and tunnels under the plateau and have the party go after Korth as mop up.
Anyway, I am looking forward to seeing this thread continue. :D