Conan is a lot of bang for the buck and very different from DnD. This is not just a splat book filled with a bunch of new, untested feats and half-baked prestige classes. Matter of fact there are no prestige classes and only a handfull of new feats (but those new feats are very flavorful). What you do get is a entirely new set of base classes, some new rules cocerning level advancement (skill points from Int can be spent on any skill, cap HP at level 10, favored class gives bonus feats instead of penalties) and a combat system that has been given a complete overhaul (armor as DR, AC split between two values (parry and dodge), harsher massive damage, weapon damage upgraded, spring attack for everyone, add base reflex save to Init). And, perhaps most importantly of all, DnD's Vancian magic system has been riped out entierly and replaced with a whole new system which is perfectly tuned to the gritty, risky, unwholesome, scarry, but not "low magic" style of Howard's world. This is something that DnD magic just cannot do for you, no mattar how much you house rule it. The bestiary section is a little light on monsters for my taste but it gives you the idea and it shouldn't be too hard to modify/custom build some creepy crawlies to kill all your players.
Long story short: $50 is a big nut to drop, especially with all the typos, but the book is massive, beautifully illistruated, and the rules themselves are rock solid (once you get past the aforementioned typos). This is not a supplement for your DnD game, but if you want a pulpy action filled Swords 'n Sorcery game then this is the best I've seen in a long time.