This is a very mediocre adventure in many ways. In comparison to the Sunless Citadel, Forge of Fury lacked the fine writing that made Sunless Citadel fun to read as well as to play. There were enough nice things about Forge of Fury that I had to give it four stars.
First, I think it continues in the tradition of Sunless Citadel by showcasing the third edition and by helping the DM with its many sidebars and hints. In fact, I believe it does an even better job of helping the DM with new third edition rules. Secondly, it also showcases many of the creatures from third edition and it makes these creatures intelligent and worthy opponents. Third, it gives the players a slight chance to negotiate with one set of opponents and to surrender to a different one. I love when role-playing adventures actually suggest tactics that don't include "kill everything you see" and Forge of Fire does an excellent job with that. Now, onto the problems with the Forge of Fury.
This adventure brings first edition AD&D to mind with its large dungeons populated by creatures that seem to have little interaction. Though annoying, it's reasonably well explained. Also, a pet peeve of mine with Forge of Fury was the fact that there were so many coins. True, many of them are silver, but it made me wonder where they got the treasure since the dungeon is explicitly not located near any towns. Lastly, in many places the adventure states that treasure is hidden in the room, but doesn't give you a general search DC to use.
This adventure is rather hard, a killer in fact near the end of it. I suggest that a DM give the players many chances to break and rest. Some of the traps and creatures can outright kill players if they don't get chances to stop and get back spells. The cleric's ability to convert spells to healing will come in handy. PCs should be around third level when they begin this adventure. All in all, I recommend this because true to how it's described, it "highlights" third edition D&D.