The Entry Proof rating scale is based on a 5 point system in a effort to simply scoring. Ratings are representative of quality and do not factor in cost or value.
Nix (1 - 1.5) - Not fit for human consumption. If my options were this or nothing I would go with a Shirley Temple. Seriously, this is a terribly whiskey with unforgivable flaws and no redeeming qualities. Examples include Cinnamon Whiskey.
Mix (2 - 2.5) - Try at a bar or seek out a sample before purchasing. May exhibit some flaws but would work in a pinch for a mixed drink. Why else do coke and ginger ale exist? Examples include Evan Williams BIB, JW Dant BIB, and Rittenhouse Rye BIB.
Sip (3 - 3.5) - Solid, everyday sipper that not only works neat but won't make you feel dirty when mixed. No flaws but might fall short in one of the major categories including nose, palate, and/or finish. Examples include Evan Williams Single Barrel, Henry McKenna BIB, and High West Double Rye.
Savor (4 - 4.5) - A true leviathan in all aspects from start to finish. Well balanced, complex and very enjoyable. This is meant for sitting back in your favorite chair and contemplating the intricacies of the universe. Examples include Smooth Ambler Old Scout Ryes and Bookers.
Thirst (5) - We are entering into mythical beast territory here. A 5 is reserved for perfection in every category. These animals are typically rare, and highly sought after making it difficult to acquire. However, something this good needs to be experienced and should be if the situation presents itself. Examples include nothing I have yet to imbibe.