I'm a big fan of Monte Cook's Arcana Unearthed, but this is my least favorite product in the line. Mystic Eye Games tries to make an adventure spanning 1st-5th levels, but this oddly-paced adventure's low production values make it hard to keep on the shelf next to the other AU titles. That said, despite the large amount of tinkering, I will probably run this adventure (at least in part) for my players at some point.
I'm wondering if there can be such a thing as too much customization in a pregenerated adventure. Normally, I would say no, but Siege on Ebonring Keep tries to be everything to everyone. There are micro-encounters in sidebars throughout the module for "roleplaying-heavy" groups. Come on, just put these paragraphs in the adventure like normal and any GM with half a brain will decide whether or not to use any specific part, just like usual. In addition, there are sidebars for encounters to add for parties with flying characters (like faen). This is probably a good idea, but since Tiny flying PCs are a huge headache for everyone else sitting at the table, I don't allow them in the first place. Another mistake is adding sidebars to drastically change the level of the adventure if the party has already played through "Plague of Dreams" - an appendix on Scaling the Adventure (a la Dungeon magazine) would do the job more efficiently.
The B&W art in the module is not terribly impressive, and doesn't do much to add to the adventure. Player handouts are gathered in an appendix, which is handy. I understand that AU's Lands of the Diamond Throne is a unique setting that was probably hard to capture the essence of on a one-shot, so my rating really ought to be 3.5 stars, but I wouldn't round it up to 4. This adventure had a lot of potential, but too often falls short.