The 1867-S Half Dollar is fairly common in most grades up to Mint State, then it becomes quite scarce up to MS63. In MS64 and better grades, the 1867-S is a true rarity. There is, however, one standout -- the PCGS MS66 Eliasberg-Gardner coin that sold recently (2014) for $19,975 - this coin is a full two pints above any other 1867-S Half Dollar certified by PCGS.
The mintmarks on this date are all minute, though one appears larger because it has been repunched.
The strike on 1867-S Half Dollars is usually soft on the obverse stars, though there are some examples that show better strikes than others.