The 1794 Half Cent is a modified version of the 1793 Liberty Cap Half Cent, with the head of Liberty turned so she is facing right. There are two major sub-types for this year: Low-relief Head and High-Relief Head. Large and Small Letter edge variants appear only on the Low Relief Heads; rarity depends on the variety with which it appears.
As a date, 1794 Half Cents are relatively common, certainly more so than the 1793. Clean, problem-free examples are very scarce and Mint State examples are very rare. Any example with even a trace of mint red is rare, and no full red examples are known. The most desirable examples are those with glossy surfaces. Heavy discounts apply to coins with pitted surfaces, obvious planchet flaws, or damage.
Varieties (9, plus subvarieties):
Low Relief Head:
Cohen 1 - Scarce
Cohen 2 - Common
Cohen 3 - Rare
Cohen 4 - Scarce
Cohen 5 - Very Scarce
Cohen 6 - Very Rare
High Relief Head:
Cohen 7 - Rare
Cohen 8 - Rare
Cohen 9 - Common
Sources and/or recommended reading:
"American Half Cents - The 'Little Half Sisters' (Second Edition)" by Roger S. Cohen, Jr.
"Walter Breen's Encyclopedia of United States Half Cents 1793-1857" by Walter Breen
Relevant collector organizations:
Early American Coppers Club