I have both played and run this module. As a DM, I found that the Season 8 format made the organization of this module annoying (lots of page flipping, plus the page numbers are missing and/or hard to read without a printer-friendly version), but that the module author did a pretty okay job of sequencing content within those constraints. It is particularly annoying that a critical NPC, location, and bit of content for the very beginning of the story is tucked away in the Appendix for its Bonus Objective (but I fault the required format, not the author).
Content-wise, I found the module offered plenty of non-combat opportunities for resolving challenges, if/when the players took their characters that way. I did find a lot of context / content about the mine, communing with the mine, the details of this, that and the other that can help fill as much time as the DM wants with stretching out the descriptions, but don't materially contribute to advancing the plot (or affect the outcome).
I found the initial encounter / encounters with the mine shaft and the trap somewhat under-specified (and information about what check with what DC for which piece spread across multiple pages and sidebars). I made something up, but I felt like the author only gave me the broadest strokes of how it should have worked. This is certainly one place where the sketched maps were less helpful than something with more labels would have been.
Difficulty-wise, I haven't seen this module challenge a party, even when shifting the difficulty up a bit beyond what the APL suggests. It's just not that deadly (which is fine, unless you're looking for that. If you are, consider significantly revising Tev's spell list and/or giving him additional minions, and give the enemies in the opening encounter bows).
Time-wise, each time I've seen this module come in around 2.5 hours, often a little under, including the Bonus Objectives. One of the players at my table said one time he'd seen it go really long (playing a different character), but otherwise that matches the other experiences I've heard.
One final note: This module essentially ends on the doorstep of its sequel, but this module is optimized for APL 5 and that module is optimized for APL 8 (and each module only gives out 1/2 a level in ACP). That means that if you do play them as a unit, the party is likely very over- or under-powered for one of them. The third in the trilogy is APL 10(!), so a DM who wants to run the trilogy together should do some careful planning and likely lots of scaling. If you don't run them as a trilogy, though, pay attention to what's basically a Story Item in the final encounter, since it's necessary for the sequel.