An unusual variety among the 1798 Half Eagles is the 14-star reverse -- all others show only 13 stars. This variety is very scarce because of the failure of the reverse, which ultimately cracked extensively and led to the splitting apart of the die. A nice example of a late (possibly terminal state) appeared as lot 5307 in Heritage's 4/2015 sale.
Only one or two low-end Mint State examples are known, one of which is in the National Numismatic Collection at the Smithsonian Institution. Numerous AU examples exist.