Having recently purchased and very much enjoyed ICONS, it was a given that I'd buy The Skeletron Key. It's written by Steve Kenson, the lead designer of ICONS with a game pedigree that includes M&M, True20, Blue Rose and more. Sold.
The Skeletron Key is a relatively short adventure for the ICONS Superpowered Roleplaying Game. The art style is identical to ICONS, with ample evocative art to capture the feel of the adventure. If I were being completely honest, when first downloaded, I was a tad concerned that there wasn't going to be much adventure in this PDF. The sales blurb clearly says that the PDF is pretty short, coming in at about 14 pages (13 with cover), and I wasn't sure how much good stuff could be fit into such a small product. I should have simply trusted that Mr. Kenson can get a lot done within a few pages - he has before, and has done so again. There is plenty of game here, and any concerns I had were unfounded.
The Skeletron Key is a pretty straightforward adventure that details the origin of an interesting new adversary - and also gives GMs and Players new to ICONS a clear and concise introduction to how to formulate adventures. I can't say a whole lot without perhaps giving away spoilers, but the tale is one which is paced well, provides a few pointers on how to get players back on track in the event that they stray off course, and lastly, provides a few memorable characters to add to your ICONS campaign - both good and bad. The main adversary reminds me very much of one of my favorite Marvel villains...so simply having him as a benchmark to build other characters was worth the price of admission alone.
Overall, this is a very good starting point for any ICONS game, and a fun adventure to boot. Well worth $5.