I've played through this twice now (used a star replay) and had interesting experieces both times. The first time was online with my, and while the party was filled with strong PC's only had an okay time because people couldn't work together. The second time was at a local con with people that worked well together and had a blast, even though we weren't as optimized. We did fine both times.
I like how the first two Bonekeeps felt like completely different challenges to me. One was trickier and made me think more, while Two was a much more visceral fight for survival. Two was a much swingier experience, with things feeling like our survival was balanced on a razor's edge the entire time, with a slight nudge either keeping us alive for another room or ending our run right then and there.
I've run this twice now, and both parties have responded well to the scenario. The NPC from this scenario is cool, both tables liked the NPC. The scenario is easy to prep, the maps are easy to draw and fit pretty well (except for the alley). The scenario hasn't gone over four hours in two times GM'ing and one time playing. If you get the chance run Black Waters first before running this. All of the encounters can be resolved peacefully, which can be a double-edged sword.
I just ran ths yesterday, and it is now one of my favorite scenarios to date. While reading the scenario during prep I knew that if it played half as well as it read I would not be disappointed, and I wasn't. The scenario has a little something for everyone: ample roleplaying opportunity, good fights, cool baddies (something I've noticed in the other Jim Groves scenario I've played, Haunting at Hinojai), some opportunities for some hilarity, and plenty of danger. There wasn't really any point that the party felt at ease, it was really nice to keep people on their toes.
Just played his scenario on Monday, and was impressed. The difficulty in this scenario is high, and the first encounter hits hard right out of the gate, it was daunting at first but once we settled down it went well. The inclusion of another player's seeker in the scenario was really cool, and I hope we see more of that in the future. There wasn't too much in the way of RP in the scenario, there is some in the final encounter(s), I count the final two as the same encounter, although that will vary from table to table, depending on how the NPC's are presented. The optional encounter is pretty neat, but my other party members murder-hobo'ed through it fast enough to prevnt any RP with the things from occurring. The first and final encounter can be very long and grindy. The inclusion of hard mode was a plus, I wish I would have gotten to experience it.
The bottom line is if you like challenging, combat heavy encounters and don't mind that there isn't a whole lot of RP (unless the table really works for it), then this scenario is for you.
This has easily been my favorite scenario to GM this season(and to play!). Being able to let the party use their brains and wits to complete the scenario without having to resort to violence was refreshing. The Guardian was great, my players all seemed to like him, I tried to give him a Sean Connery-ish voice. If you run this, it is very important to be well prepared, moreso than usual. I would recommend that people make sure that their party understands that this is an investigative scenario, so they don't bring the wrong character to the game.