The game is GREAT. One of the best adaptations of d20, in my opinion. A lot of the dislike for it you find was based on the fact that the first edition was ruined by poor editing... maybe no editing. Of course, you don't have to worry about that. Just buy the Atlantean Edition which corrects the typos, adds better descriptions, explanations and diagrams. (It actually says "Atlantean Edition" on the cover.) The PDF is available on DriveThruRPG.com and the pocket edition of the rules is due out this month.
Now, to the system -- the classes are all new and are designed to fit the Conan stories. Barbarians are like Conan. Soldiers are like the soldiers he fought. Thieves are like the thieves in the stories. Nomads are like the nomads, etc. Multiclassing is encouraged.
Races are numerous and fit the various races Howard came up with for his mythic past. Cimmerians, Hyborians, Himelians, Stygian, Kushite, etc. Each race has special abilities and skill bonuses as well as favored classes.
Combat is mainly changed by including a couple new mechanics. First, armor provides Damage Reduction. Second, every class progresses in two different styles of defense -- parry and dodge. Dodge is based on DEX, Parry on STR. When attacked, a character chooses which to use. Penalties for two-handed fighting are minor, to account for how common it was in Howard stories. Plus, there are some combat maneuvers -- like feats, except anyone who qualifies for the pre-reqs can use them. There are a number of new Howardian feats, as well.
The magic system is detailed in the thread here on alternate d20 Magic systems. Trust me, it fits Howard's vision to a tee.
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